81377725 has 72 divisors (see below), whose sum is σ = 127438272. Its totient is φ = 50918400.

The previous prime is 81377713. The next prime is 81377729. The reversal of 81377725 is 52777318.

It is not a de Polignac number, because 81377725 - 2²³ = 72989117 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81377729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 790024 + ... + 790126.

It is an arithmetic number, because the mean of its divisors is an integer number (1769976).

Almost surely, 2^81377725 is an apocalyptic number.

81377725 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

It is an amenable number.

81377725 is a deficient number, since it is larger than the sum of its proper divisors (46060547).

81377725 is a wasteful number, since it uses less digits than its factorization.

81377725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167 (or 149 counting only the distinct ones).

The product of its digits is 82320, while the sum is 40.

The square root of 81377725 is about 9020.9603147337. The cubic root of 81377725 is about 433.3463884956.

The spelling of 81377725 in words is "eighty-one million, three hundred seventy-seven thousand, seven hundred twenty-five".