81902500 has 45 divisors (see below), whose sum is σ = 180099381. Its totient is φ = 32580000.

The previous prime is 81902479. The next prime is 81902507. The reversal of 81902500 is 520918.

The square root of 81902500 is 9050.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 7 ways, for example, as 79316836 + 2585664 = 8906^2 + 1608^2 .

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81902507) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 452410 + ... + 452590.

Almost surely, 2^81902500 is an apocalyptic number.

81902500 is the 9050-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81902500

81902500 is an abundant number, since it is smaller than the sum of its proper divisors (98196881).

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

81902500 is an equidigital number, since it uses as much as digits as its factorization.

81902500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 386 (or 188 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 25.

The cubic root of 81902500 is about 434.2758904708.

Multiplying 81902500 by its sum of digits (25), we get a square (2047562500 = 45250²).

81902500 divided by its sum of digits (25) gives a square (3276100 = 1810²).

It can be divided in two parts, 81 and 902500, that multiplied together give a square (73102500 = 8550²).

The spelling of 81902500 in words is "eighty-one million, nine hundred two thousand, five hundred".