431557661 has 2 divisors, whose sum is σ = 431557662. Its totient is φ = 431557660.

The previous prime is 431557639. The next prime is 431557681. The reversal of 431557661 is 166755134.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 345253561 + 86304100 = 18581^2 + 9290^2 .

It is a cyclic number.

It is not a de Polignac number, because 431557661 - 2¹⁰ = 431556637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (431557601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 215778830 + 215778831.

It is an arithmetic number, because the mean of its divisors is an integer number (215778831).

Almost surely, 2^431557661 is an apocalyptic number.

It is an amenable number.

431557661 is a deficient number, since it is larger than the sum of its proper divisors (1).

431557661 is an equidigital number, since it uses as much as digits as its factorization.

431557661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 75600, while the sum is 38.

The square root of 431557661 is about 20773.9659429778. The cubic root of 431557661 is about 755.6945269081.

The spelling of 431557661 in words is "four hundred thirty-one million, five hundred fifty-seven thousand, six hundred sixty-one".