90921813 has 4 divisors (see below), whose sum is σ = 121229088. Its totient is φ = 60614540.

The previous prime is 90921767. The next prime is 90921827. The reversal of 90921813 is 31812909.

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 90921813 - 2⁶ = 90921749 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (90921833) 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, 15153633 + ... + 15153638.

It is an arithmetic number, because the mean of its divisors is an integer number (30307272).

Almost surely, 2^90921813 is an apocalyptic number.

It is an amenable number.

90921813 is a deficient number, since it is larger than the sum of its proper divisors (30307275).

90921813 is a wasteful number, since it uses less digits than its factorization.

90921813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30307274.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 90921813 is about 9535.2930211924. The cubic root of 90921813 is about 449.6652869023.

It can be divided in two parts, 909 and 21813, that added together give a palindrome (22722).

The spelling of 90921813 in words is "ninety million, nine hundred twenty-one thousand, eight hundred thirteen".