81644290 has 64 divisors (see below), whose sum is σ = 184665600. Its totient is φ = 25824960.

The previous prime is 81644267. The next prime is 81644323. The reversal of 81644290 is 9244618.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 43675 + ... + 45505.

It is an arithmetic number, because the mean of its divisors is an integer number (2885400).

Almost surely, 2^81644290 is an apocalyptic number.

81644290 is an abundant number, since it is smaller than the sum of its proper divisors (103021310).

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

81644290 is a wasteful number, since it uses less digits than its factorization.

81644290 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1872 (or 1858 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 34.

The square root of 81644290 is about 9035.7229926553. The cubic root of 81644290 is about 433.8190365909.

The spelling of 81644290 in words is "eighty-one million, six hundred forty-four thousand, two hundred ninety".