661929131 has 2 divisors, whose sum is σ = 661929132. Its totient is φ = 661929130.

The previous prime is 661929109. The next prime is 661929139. The reversal of 661929131 is 131929166.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661929131 is a prime.

It is a super-2 number, since 2×661929131² = 876300348932830322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661929139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330964565 + 330964566.

It is an arithmetic number, because the mean of its divisors is an integer number (330964566).

Almost surely, 2^661929131 is an apocalyptic number.

661929131 is a deficient number, since it is larger than the sum of its proper divisors (1).

661929131 is an equidigital number, since it uses as much as digits as its factorization.

661929131 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17496, while the sum is 38.

The square root of 661929131 is about 25727.9834227248. The cubic root of 661929131 is about 871.5062342744.

The spelling of 661929131 in words is "six hundred sixty-one million, nine hundred twenty-nine thousand, one hundred thirty-one".