661911610 has 16 divisors (see below), whose sum is σ = 1210973832. Its totient is φ = 260424000.

The previous prime is 661911589. The next prime is 661911617. The reversal of 661911610 is 16119166.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 426381201 + 235530409 = 20649^2 + 15347^2 .

It is not an unprimeable number, because it can be changed into a prime (661911617) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 541941 + ... + 543160.

Almost surely, 2^661911610 is an apocalyptic number.

661911610 is a deficient number, since it is larger than the sum of its proper divisors (549062222).

661911610 is a wasteful number, since it uses less digits than its factorization.

661911610 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085169.

The product of its (nonzero) digits is 1944, while the sum is 31.

The square root of 661911610 is about 25727.6429157434. The cubic root of 661911610 is about 871.4985447325.

The spelling of 661911610 in words is "six hundred sixty-one million, nine hundred eleven thousand, six hundred ten".