661503520 has 48 divisors (see below), whose sum is σ = 1588445208. Its totient is φ = 260259840.

The previous prime is 661503511. The next prime is 661503539. The reversal of 661503520 is 25305166.

It can be written as a sum of positive squares in 4 ways, for example, as 406909584 + 254593936 = 20172^2 + 15956^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 24129 + ... + 43648.

Almost surely, 2^661503520 is an apocalyptic number.

It is an amenable number.

661503520 is an abundant number, since it is smaller than the sum of its proper divisors (926941688).

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

661503520 is a wasteful number, since it uses less digits than its factorization.

661503520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67853 (or 67845 counting only the distinct ones).

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 661503520 is about 25719.7107293220. The cubic root of 661503520 is about 871.3194055288.

Adding to 661503520 its reverse (25305166), we get a palindrome (686808686).

The spelling of 661503520 in words is "six hundred sixty-one million, five hundred three thousand, five hundred twenty".