81955320 has 64 divisors (see below), whose sum is σ = 253808640. Its totient is φ = 21148800.

The previous prime is 81955297. The next prime is 81955343. The reversal of 81955320 is 2355918.

It is an interprime number because it is at equal distance from previous prime (81955297) and next prime (81955343).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7296 + ... + 14735.

It is an arithmetic number, because the mean of its divisors is an integer number (3965760).

Almost surely, 2^81955320 is an apocalyptic number.

It is an amenable number.

81955320 is an abundant number, since it is smaller than the sum of its proper divisors (171853320).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81955320 is a wasteful number, since it uses less digits than its factorization.

81955320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22076 (or 22072 counting only the distinct ones).

The product of its (nonzero) digits is 10800, while the sum is 33.

The square root of 81955320 is about 9052.9177616943. The cubic root of 81955320 is about 434.3692271544.

The spelling of 81955320 in words is "eighty-one million, nine hundred fifty-five thousand, three hundred twenty".