90918221 has 4 divisors (see below), whose sum is σ = 91768032. Its totient is φ = 90068412.

The previous prime is 90918187. The next prime is 90918239. The reversal of 90918221 is 12281909.

It is a happy number.

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 a de Polignac number, because none of the positive numbers 2^k-90918221 is a prime.

It is a super-2 number, since 2×90918221² = 16532245819609682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90918251) 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, 424745 + ... + 424958.

It is an arithmetic number, because the mean of its divisors is an integer number (22942008).

Almost surely, 2^90918221 is an apocalyptic number.

It is an amenable number.

90918221 is a deficient number, since it is larger than the sum of its proper divisors (849811).

90918221 is a wasteful number, since it uses less digits than its factorization.

90918221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849810.

The product of its (nonzero) digits is 2592, while the sum is 32.

The square root of 90918221 is about 9535.1046664418. The cubic root of 90918221 is about 449.6593652614.

The spelling of 90918221 in words is "ninety million, nine hundred eighteen thousand, two hundred twenty-one".