81957120 has 144 divisors (see below), whose sum is σ = 299241600. Its totient is φ = 18726912.

The previous prime is 81957101. The next prime is 81957167. The reversal of 81957120 is 2175918.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25356 + ... + 28404.

Almost surely, 2^81957120 is an apocalyptic number.

81957120 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81957120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (149620800).

81957120 is an abundant number, since it is smaller than the sum of its proper divisors (217284480).

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

81957120 is a wasteful number, since it uses less digits than its factorization.

81957120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3080 (or 3066 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 81957120 is about 9053.0171766102. The cubic root of 81957120 is about 434.3724071753.

The spelling of 81957120 in words is "eighty-one million, nine hundred fifty-seven thousand, one hundred twenty".