661502220520 has 32 divisors (see below), whose sum is σ = 1493228167200. Its totient is φ = 263738991168.

The previous prime is 661502220481. The next prime is 661502220539. The reversal of 661502220520 is 25022205166.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 26921850 + ... + 26946409.

It is an arithmetic number, because the mean of its divisors is an integer number (46663380225).

Almost surely, 2^661502220520 is an apocalyptic number.

It is an amenable number.

661502220520 is an abundant number, since it is smaller than the sum of its proper divisors (831725946680).

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

661502220520 is a wasteful number, since it uses less digits than its factorization.

661502220520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53868577 (or 53868573 counting only the distinct ones).

The product of its (nonzero) digits is 14400, while the sum is 31.

Adding to 661502220520 its reverse (25022205166), we get a palindrome (686524425686).

The spelling of 661502220520 in words is "six hundred sixty-one billion, five hundred two million, two hundred twenty thousand, five hundred twenty".