81253836 has 18 divisors (see below), whose sum is σ = 205391732. Its totient is φ = 27084600.

The previous prime is 81253819. The next prime is 81253859. The reversal of 81253836 is 63835218.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 2257051 = 81253836 / (8 + 1 + 2 + 5 + 3 + 8 + 3 + 6).

It is a self number, because there is not a number n which added to its sum of digits gives 81253836.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1128490 + ... + 1128561.

Almost surely, 2^81253836 is an apocalyptic number.

It is an amenable number.

81253836 is an abundant number, since it is smaller than the sum of its proper divisors (124137896).

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

81253836 is a wasteful number, since it uses less digits than its factorization.

81253836 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2257061 (or 2257056 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 81253836 is about 9014.0909691438. The cubic root of 81253836 is about 433.1263687544.

The spelling of 81253836 in words is "eighty-one million, two hundred fifty-three thousand, eight hundred thirty-six".