90508021 has 2 divisors, whose sum is σ = 90508022. Its totient is φ = 90508020.

The previous prime is 90508007. The next prime is 90508049. The reversal of 90508021 is 12080509.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 73788100 + 16719921 = 8590^2 + 4089^2 .

It is a cyclic number.

It is not a de Polignac number, because 90508021 - 2⁹ = 90507509 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90508721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45254010 + 45254011.

It is an arithmetic number, because the mean of its divisors is an integer number (45254011).

Almost surely, 2^90508021 is an apocalyptic number.

It is an amenable number.

90508021 is a deficient number, since it is larger than the sum of its proper divisors (1).

90508021 is an equidigital number, since it uses as much as digits as its factorization.

90508021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 90508021 is about 9513.5703602801. The cubic root of 90508021 is about 448.9820959357.

It can be divided in two parts, 9050 and 8021, that added together give a palindrome (17071).

The spelling of 90508021 in words is "ninety million, five hundred eight thousand, twenty-one".