661878613224 has 640 divisors, whose sum is σ = 2087377776000. Its totient is φ = 195649800192.

The previous prime is 661878613211. The next prime is 661878613237. The reversal of 661878613224 is 422316878166.

It is a happy number.

661878613224 is a `hidden beast` number, since 6 + 6 + 18 + 7 + 8 + 613 + 2 + 2 + 4 = 666.

It is an interprime number because it is at equal distance from previous prime (661878613211) and next prime (661878613237).

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

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 6185781379 + ... + 6185781485.

It is an arithmetic number, because the mean of its divisors is an integer number (3261527775).

Almost surely, 2^661878613224 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 661878613224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1043688888000).

661878613224 is an abundant number, since it is smaller than the sum of its proper divisors (1425499162776).

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

661878613224 is a wasteful number, since it uses less digits than its factorization.

661878613224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 225 counting only the distinct ones).

The product of its digits is 4644864, while the sum is 54.

The spelling of 661878613224 in words is "six hundred sixty-one billion, eight hundred seventy-eight million, six hundred thirteen thousand, two hundred twenty-four".