81122724 has 18 divisors (see below), whose sum is σ = 205060310. Its totient is φ = 27040896.

The previous prime is 81122719. The next prime is 81122731. The reversal of 81122724 is 42722118.

It can be written as a sum of positive squares in only one way, i.e., 73102500 + 8020224 = 8550^2 + 2832^2 .

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

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, 1126669 + ... + 1126740.

Almost surely, 2^81122724 is an apocalyptic number.

It is an amenable number.

81122724 is an abundant number, since it is smaller than the sum of its proper divisors (123937586).

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

81122724 is a wasteful number, since it uses less digits than its factorization.

81122724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2253419 (or 2253414 counting only the distinct ones).

The product of its digits is 1792, while the sum is 27.

The square root of 81122724 is about 9006.8154194477. The cubic root of 81122724 is about 432.8932776608.

The spelling of 81122724 in words is "eighty-one million, one hundred twenty-two thousand, seven hundred twenty-four".