81244920 has 32 divisors (see below), whose sum is σ = 243735120. Its totient is φ = 21665280.

The previous prime is 81244907. The next prime is 81244957. The reversal of 81244920 is 2944218.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 338401 + ... + 338640.

Almost surely, 2^81244920 is an apocalyptic number.

It is an amenable number.

81244920 is an abundant number, since it is smaller than the sum of its proper divisors (162490200).

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

81244920 is a wasteful number, since it uses less digits than its factorization.

81244920 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 677055 (or 677051 counting only the distinct ones).

The product of its (nonzero) digits is 4608, while the sum is 30.

The square root of 81244920 is about 9013.5963965556. The cubic root of 81244920 is about 433.1105258266.

The spelling of 81244920 in words is "eighty-one million, two hundred forty-four thousand, nine hundred twenty".