661910531 has 4 divisors (see below), whose sum is σ = 664801200. Its totient is φ = 659019864.

The previous prime is 661910527. The next prime is 661910539. The reversal of 661910531 is 135019166.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 661910531 - 2² = 661910527 is a prime.

It is a super-2 number, since 2×661910531² = 876251102097403922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (661910539) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1444991 + ... + 1445448.

It is an arithmetic number, because the mean of its divisors is an integer number (166200300).

Almost surely, 2^661910531 is an apocalyptic number.

661910531 is a deficient number, since it is larger than the sum of its proper divisors (2890669).

661910531 is a wasteful number, since it uses less digits than its factorization.

661910531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2890668.

The product of its (nonzero) digits is 4860, while the sum is 32.

The square root of 661910531 is about 25727.6219460719. The cubic root of 661910531 is about 871.4980711811.

Adding to 661910531 its reverse (135019166), we get a palindrome (796929697).

The spelling of 661910531 in words is "six hundred sixty-one million, nine hundred ten thousand, five hundred thirty-one".