66813431 has 2 divisors, whose sum is σ = 66813432. Its totient is φ = 66813430.

The previous prime is 66813427. The next prime is 66813433. The reversal of 66813431 is 13431866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66813431 - 2² = 66813427 is a prime.

It is a super-2 number, since 2×66813431² = 8928069123983522, which contains 22 as substring.

Together with 66813433, 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 (66813433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33406715 + 33406716.

It is an arithmetic number, because the mean of its divisors is an integer number (33406716).

Almost surely, 2^66813431 is an apocalyptic number.

66813431 is a deficient number, since it is larger than the sum of its proper divisors (1).

66813431 is an equidigital number, since it uses as much as digits as its factorization.

66813431 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 32.

The square root of 66813431 is about 8173.9483115567. The cubic root of 66813431 is about 405.7774650632. Note that the first 3 decimals are identical.

The spelling of 66813431 in words is "sixty-six million, eight hundred thirteen thousand, four hundred thirty-one".