81923907 has 16 divisors (see below), whose sum is σ = 122750208. Its totient is φ = 48222240.

The previous prime is 81923893. The next prime is 81923909. The reversal of 81923907 is 70932918.

It is not a de Polignac number, because 81923907 - 2⁶ = 81923843 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is not an unprimeable number, because it can be changed into a prime (81923909) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44769 + ... + 46562.

It is an arithmetic number, because the mean of its divisors is an integer number (7671888).

Almost surely, 2^81923907 is an apocalyptic number.

81923907 is a deficient number, since it is larger than the sum of its proper divisors (40826301).

81923907 is a wasteful number, since it uses less digits than its factorization.

81923907 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 91370.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 81923907 is about 9051.1826299109. The cubic root of 81923907 is about 434.3137229918.

The spelling of 81923907 in words is "eighty-one million, nine hundred twenty-three thousand, nine hundred seven".