66987631 has 2 divisors, whose sum is σ = 66987632. Its totient is φ = 66987630.

The previous prime is 66987623. The next prime is 66987653. The reversal of 66987631 is 13678966.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 66987631 - 2³ = 66987623 is a prime.

It is a super-2 number, since 2×66987631² = 8974685413984322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66987611) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33493815 + 33493816.

It is an arithmetic number, because the mean of its divisors is an integer number (33493816).

Almost surely, 2^66987631 is an apocalyptic number.

66987631 is a deficient number, since it is larger than the sum of its proper divisors (1).

66987631 is an equidigital number, since it uses as much as digits as its factorization.

66987631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 46.

The square root of 66987631 is about 8184.5971800694. The cubic root of 66987631 is about 406.1298148305.

The spelling of 66987631 in words is "sixty-six million, nine hundred eighty-seven thousand, six hundred thirty-one".