90721889 has 12 divisors (see below), whose sum is σ = 96246780. Its totient is φ = 85411200.

The previous prime is 90721861. The next prime is 90721901. The reversal of 90721889 is 98812709.

It can be written as a sum of positive squares in 6 ways, for example, as 58140625 + 32581264 = 7625^2 + 5708^2 .

It is not a de Polignac number, because 90721889 - 2⁸ = 90721633 is a prime.

It is a super-2 number, since 2×90721889² = 16460922287456642, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90724889) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 47819 + ... + 49679.

It is an arithmetic number, because the mean of its divisors is an integer number (8020565).

Almost surely, 2^90721889 is an apocalyptic number.

It is an amenable number.

90721889 is a deficient number, since it is larger than the sum of its proper divisors (5524891).

90721889 is a wasteful number, since it uses less digits than its factorization.

90721889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1972 (or 1931 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 44.

The square root of 90721889 is about 9524.8038824954. The cubic root of 90721889 is about 449.3354619240.

The spelling of 90721889 in words is "ninety million, seven hundred twenty-one thousand, eight hundred eighty-nine".