81859923 has 16 divisors (see below), whose sum is σ = 127657600. Its totient is φ = 51700680.

The previous prime is 81859909. The next prime is 81859951. The reversal of 81859923 is 32995818.

It is a happy number.

It is not a de Polignac number, because 81859923 - 2⁶ = 81859859 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81859123) 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, 79273 + ... + 80298.

It is an arithmetic number, because the mean of its divisors is an integer number (7978600).

Almost surely, 2^81859923 is an apocalyptic number.

81859923 is a deficient number, since it is larger than the sum of its proper divisors (45797677).

81859923 is a wasteful number, since it uses less digits than its factorization.

81859923 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159599 (or 159593 counting only the distinct ones).

The product of its digits is 155520, while the sum is 45.

The square root of 81859923 is about 9047.6473737652. The cubic root of 81859923 is about 434.2006246789.

The spelling of 81859923 in words is "eighty-one million, eight hundred fifty-nine thousand, nine hundred twenty-three".