661919624 has 8 divisors (see below), whose sum is σ = 1241099310. Its totient is φ = 330959808.

The previous prime is 661919623. The next prime is 661919627. The reversal of 661919624 is 426919166.

It can be written as a sum of positive squares in only one way, i.e., 661415524 + 504100 = 25718^2 + 710^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (661919623) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 41369969 + ... + 41369984.

Almost surely, 2^661919624 is an apocalyptic number.

It is an amenable number.

661919624 is a deficient number, since it is larger than the sum of its proper divisors (579179686).

661919624 is a wasteful number, since it uses less digits than its factorization.

661919624 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 82739959 (or 82739955 counting only the distinct ones).

The product of its digits is 139968, while the sum is 44.

The square root of 661919624 is about 25727.7986621475. The cubic root of 661919624 is about 871.5020618995.

The spelling of 661919624 in words is "six hundred sixty-one million, nine hundred nineteen thousand, six hundred twenty-four".