81156921 has 8 divisors (see below), whose sum is σ = 110511744. Its totient is φ = 52953360.

The previous prime is 81156883. The next prime is 81156941. The reversal of 81156921 is 12965118.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81156921 - 2¹⁴ = 81140537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81156941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 287650 + ... + 287931.

It is an arithmetic number, because the mean of its divisors is an integer number (13813968).

Almost surely, 2^81156921 is an apocalyptic number.

It is an amenable number.

81156921 is a deficient number, since it is larger than the sum of its proper divisors (29354823).

81156921 is a wasteful number, since it uses less digits than its factorization.

81156921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 575631.

The product of its digits is 4320, while the sum is 33.

The square root of 81156921 is about 9008.7136151617. The cubic root of 81156921 is about 432.9540973302.

The spelling of 81156921 in words is "eighty-one million, one hundred fifty-six thousand, nine hundred twenty-one".