66806431 has 2 divisors, whose sum is σ = 66806432. Its totient is φ = 66806430.

The previous prime is 66806387. The next prime is 66806473. The reversal of 66806431 is 13460866.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 66806431 - 2¹¹ = 66804383 is a prime.

It is a super-2 number, since 2×66806431² = 8926198445915522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (66801431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33403215 + 33403216.

It is an arithmetic number, because the mean of its divisors is an integer number (33403216).

Almost surely, 2^66806431 is an apocalyptic number.

66806431 is a deficient number, since it is larger than the sum of its proper divisors (1).

66806431 is an equidigital number, since it uses as much as digits as its factorization.

66806431 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 34.

The square root of 66806431 is about 8173.5201106989. The cubic root of 66806431 is about 405.7632935540.

The spelling of 66806431 in words is "sixty-six million, eight hundred six thousand, four hundred thirty-one".