21850913 has 6 divisors (see below), whose sum is σ = 25418466. Its totient is φ = 18729312.

The previous prime is 21850901. The next prime is 21850919. The reversal of 21850913 is 31905812.

It can be written as a sum of positive squares in only one way, i.e., 21603904 + 247009 = 4648^2 + 497^2 .

It is not a de Polignac number, because 21850913 - 2⁶ = 21850849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21850919) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 222920 + ... + 223017.

It is an arithmetic number, because the mean of its divisors is an integer number (4236411).

Almost surely, 2^21850913 is an apocalyptic number.

It is an amenable number.

21850913 is a deficient number, since it is larger than the sum of its proper divisors (3567553).

21850913 is an equidigital number, since it uses as much as digits as its factorization.

21850913 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445951 (or 445944 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 21850913 is about 4674.4960156149. The cubic root of 21850913 is about 279.5695469230.

The spelling of 21850913 in words is "twenty-one million, eight hundred fifty thousand, nine hundred thirteen".