661358431 has 2 divisors, whose sum is σ = 661358432. Its totient is φ = 661358430.

The previous prime is 661358419. The next prime is 661358483. The reversal of 661358431 is 134853166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661358431 - 2²¹ = 659261279 is a prime.

It is a super-2 number, since 2×661358431² = 874789948509563522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661352431) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330679215 + 330679216.

It is an arithmetic number, because the mean of its divisors is an integer number (330679216).

Almost surely, 2^661358431 is an apocalyptic number.

661358431 is a deficient number, since it is larger than the sum of its proper divisors (1).

661358431 is an equidigital number, since it uses as much as digits as its factorization.

661358431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 37.

The square root of 661358431 is about 25716.8899947097. The cubic root of 661358431 is about 871.2556980800.

The spelling of 661358431 in words is "six hundred sixty-one million, three hundred fifty-eight thousand, four hundred thirty-one".