661778501402304 has 1344 divisors, whose sum is σ = 2448412206170112. Its totient is φ = 174121087795200.

The previous prime is 661778501402299. The next prime is 661778501402309. The reversal of 661778501402304 is 403204105877166.

661778501402304 is a `hidden beast` number, since 6 + 6 + 1 + 7 + 78 + 501 + 40 + 23 + 0 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (661778501402299) and next prime (661778501402309).

It is a super-3 number, since 3×661778501402304³ (a number of 45 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (661778501402309) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 80793366849 + ... + 80793375039.

It is an arithmetic number, because the mean of its divisors is an integer number (1821735272448).

Almost surely, 2^{661778501402304} is an apocalyptic number.

661778501402304 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661778501402304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1224206103085056).

661778501402304 is an abundant number, since it is smaller than the sum of its proper divisors (1786633704767808).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661778501402304 is a wasteful number, since it uses less digits than its factorization.

661778501402304 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10396 (or 10374 counting only the distinct ones).

The product of its (nonzero) digits is 6773760, while the sum is 54.

The spelling of 661778501402304 in words is "six hundred sixty-one trillion, seven hundred seventy-eight billion, five hundred one million, four hundred two thousand, three hundred four".