909100021 has 2 divisors, whose sum is σ = 909100022. Its totient is φ = 909100020.

The previous prime is 909100013. The next prime is 909100051. The reversal of 909100021 is 120001909.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 542377521 + 366722500 = 23289^2 + 19150^2 .

It is a cyclic number.

It is not a de Polignac number, because 909100021 - 2³ = 909100013 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 909099965 and 909100001.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (909100051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 454550010 + 454550011.

It is an arithmetic number, because the mean of its divisors is an integer number (454550011).

Almost surely, 2^909100021 is an apocalyptic number.

It is an amenable number.

909100021 is a deficient number, since it is larger than the sum of its proper divisors (1).

909100021 is an equidigital number, since it uses as much as digits as its factorization.

909100021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162, while the sum is 22.

The square root of 909100021 is about 30151.2855613156. The cubic root of 909100021 is about 968.7325426976.

The spelling of 909100021 in words is "nine hundred nine million, one hundred thousand, twenty-one".