66685631 has 2 divisors, whose sum is σ = 66685632. Its totient is φ = 66685630.

The previous prime is 66685609. The next prime is 66685637. The reversal of 66685631 is 13658666.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66685631 - 2¹⁴ = 66669247 is a prime.

It is a super-2 number, since 2×66685631² = 8893946763736322, which contains 22 as substring.

It is a Sophie Germain 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 (66685637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33342815 + 33342816.

It is an arithmetic number, because the mean of its divisors is an integer number (33342816).

Almost surely, 2^66685631 is an apocalyptic number.

66685631 is a deficient number, since it is larger than the sum of its proper divisors (1).

66685631 is an equidigital number, since it uses as much as digits as its factorization.

66685631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 41.

The square root of 66685631 is about 8166.1270501995. The cubic root of 66685631 is about 405.5185776951.

The spelling of 66685631 in words is "sixty-six million, six hundred eighty-five thousand, six hundred thirty-one".