66615431 has 2 divisors, whose sum is σ = 66615432. Its totient is φ = 66615430.

The previous prime is 66615427. The next prime is 66615433. The reversal of 66615431 is 13451666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66615431 - 2² = 66615427 is a prime.

It is a super-2 number, since 2×66615431² = 8875231294631522, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 66615433, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66615433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33307715 + 33307716.

It is an arithmetic number, because the mean of its divisors is an integer number (33307716).

Almost surely, 2^66615431 is an apocalyptic number.

66615431 is a deficient number, since it is larger than the sum of its proper divisors (1).

66615431 is an equidigital number, since it uses as much as digits as its factorization.

66615431 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 32.

The square root of 66615431 is about 8161.8276752208. The cubic root of 66615431 is about 405.3762311916.

The spelling of 66615431 in words is "sixty-six million, six hundred fifteen thousand, four hundred thirty-one".