90123721 has 4 divisors (see below), whose sum is σ = 90663552. Its totient is φ = 89583892.

The previous prime is 90123697. The next prime is 90123731. The reversal of 90123721 is 12732109.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 90123721 - 2⁵ = 90123689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (90123731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 269665 + ... + 269998.

It is an arithmetic number, because the mean of its divisors is an integer number (22665888).

Almost surely, 2^90123721 is an apocalyptic number.

It is an amenable number.

90123721 is a deficient number, since it is larger than the sum of its proper divisors (539831).

90123721 is a wasteful number, since it uses less digits than its factorization.

90123721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 539830.

The product of its (nonzero) digits is 756, while the sum is 25.

The square root of 90123721 is about 9493.3514103292. The cubic root of 90123721 is about 448.3457302150.

The spelling of 90123721 in words is "ninety million, one hundred twenty-three thousand, seven hundred twenty-one".