661365227952 has 720 divisors, whose sum is σ = 2366498534400. Its totient is φ = 169510579200.

The previous prime is 661365227947. The next prime is 661365228011. The reversal of 661365227952 is 259722563166.

It is a happy number.

661365227952 is a `hidden beast` number, since 6 + 6 + 1 + 365 + 2 + 279 + 5 + 2 = 666.

It is a super-2 number, since 2×661365227952² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 375988449 + ... + 375990207.

It is an arithmetic number, because the mean of its divisors is an integer number (3286803520).

Almost surely, 2^661365227952 is an apocalyptic number.

661365227952 is a gapful number since it is divisible by the number (62) 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 661365227952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1183249267200).

661365227952 is an abundant number, since it is smaller than the sum of its proper divisors (1705133306448).

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

661365227952 is a wasteful number, since it uses less digits than its factorization.

661365227952 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1878 (or 1838 counting only the distinct ones).

The product of its digits is 8164800, while the sum is 54.

The spelling of 661365227952 in words is "six hundred sixty-one billion, three hundred sixty-five million, two hundred twenty-seven thousand, nine hundred fifty-two".