661185275690 has 32 divisors (see below), whose sum is σ = 1200842753040. Its totient is φ = 262094966784.

The previous prime is 661185275683. The next prime is 661185275759. The reversal of 661185275690 is 96572581166.

It is a Cunningham number, because it is equal to 813133²+1.

It can be written as a sum of positive squares in 8 ways, for example, as 25738747489 + 635446528201 = 160433^2 + 797149^2 .

It is a super-2 number, since 2×661185275690² (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 15 ways as a sum of consecutive naturals, for example, 8341766 + ... + 8420654.

Almost surely, 2^661185275690 is an apocalyptic number.

661185275690 is a deficient number, since it is larger than the sum of its proper divisors (539657477350).

661185275690 is a wasteful number, since it uses less digits than its factorization.

661185275690 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86426.

The product of its (nonzero) digits is 5443200, while the sum is 56.

The spelling of 661185275690 in words is "six hundred sixty-one billion, one hundred eighty-five million, two hundred seventy-five thousand, six hundred ninety".