81123525 has 120 divisors (see below), whose sum is σ = 176447040. Its totient is φ = 36080640.

The previous prime is 81123517. The next prime is 81123547. The reversal of 81123525 is 52532118.

It is a happy number.

It is not a de Polignac number, because 81123525 - 2³ = 81123517 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 836277 + ... + 836373.

It is an arithmetic number, because the mean of its divisors is an integer number (1470392).

Almost surely, 2^81123525 is an apocalyptic number.

It is an amenable number.

81123525 is an abundant number, since it is smaller than the sum of its proper divisors (95323515).

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

81123525 is a wasteful number, since it uses less digits than its factorization.

81123525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185 (or 171 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 81123525 is about 9006.8598856649. The cubic root of 81123525 is about 432.8947024419.

It can be divided in two parts, 811 and 23525, that added together give a square (24336 = 156²).

The spelling of 81123525 in words is "eighty-one million, one hundred twenty-three thousand, five hundred twenty-five".