81564407 has 2 divisors, whose sum is σ = 81564408. Its totient is φ = 81564406.

The previous prime is 81564401. The next prime is 81564451. The reversal of 81564407 is 70446518.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 81564407 - 2⁸ = 81564151 is a 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 (81564401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40782203 + 40782204.

It is an arithmetic number, because the mean of its divisors is an integer number (40782204).

Almost surely, 2^81564407 is an apocalyptic number.

81564407 is a deficient number, since it is larger than the sum of its proper divisors (1).

81564407 is an equidigital number, since it uses as much as digits as its factorization.

81564407 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 26880, while the sum is 35.

The square root of 81564407 is about 9031.3015119638. The cubic root of 81564407 is about 433.6775036287.

The spelling of 81564407 in words is "eighty-one million, five hundred sixty-four thousand, four hundred seven".