81442290 has 16 divisors (see below), whose sum is σ = 195461568. Its totient is φ = 21717936.

The previous prime is 81442279. The next prime is 81442297. The reversal of 81442290 is 9224418.

It is a Harshad number since it is a multiple of its sum of digits (30), and also a Moran number because the ratio is a prime number: 2714743 = 81442290 / (8 + 1 + 4 + 4 + 2 + 2 + 9 + 0).

It is not an unprimeable number, because it can be changed into a prime (81442297) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1357342 + ... + 1357401.

It is an arithmetic number, because the mean of its divisors is an integer number (12216348).

Almost surely, 2^81442290 is an apocalyptic number.

81442290 is an abundant number, since it is smaller than the sum of its proper divisors (114019278).

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

81442290 is a wasteful number, since it uses less digits than its factorization.

81442290 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2714753.

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

The square root of 81442290 is about 9024.5382153327. The cubic root of 81442290 is about 433.4609637200.

The spelling of 81442290 in words is "eighty-one million, four hundred forty-two thousand, two hundred ninety".