66745631 has 2 divisors, whose sum is σ = 66745632. Its totient is φ = 66745630.

The previous prime is 66745607. The next prime is 66745633. The reversal of 66745631 is 13654766.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66745631 - 2¹⁰ = 66744607 is a prime.

It is a super-2 number, since 2×66745631² = 8909958515176322, which contains 22 as substring.

Together with 66745633, 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 (66745633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33372815 + 33372816.

It is an arithmetic number, because the mean of its divisors is an integer number (33372816).

Almost surely, 2^66745631 is an apocalyptic number.

66745631 is a deficient number, since it is larger than the sum of its proper divisors (1).

66745631 is an equidigital number, since it uses as much as digits as its factorization.

66745631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90720, while the sum is 38.

The square root of 66745631 is about 8169.7999363510. The cubic root of 66745631 is about 405.6401622138.

It can be divided in two parts, 66745 and 631, that added together give a palindrome (67376).

The spelling of 66745631 in words is "sixty-six million, seven hundred forty-five thousand, six hundred thirty-one".