21813607 has 4 divisors (see below), whose sum is σ = 21833680. Its totient is φ = 21793536.

The previous prime is 21813569. The next prime is 21813619. The reversal of 21813607 is 70631812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21813607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21813667) 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, 8307 + ... + 10612.

It is an arithmetic number, because the mean of its divisors is an integer number (5458420).

Almost surely, 2^21813607 is an apocalyptic number.

21813607 is a deficient number, since it is larger than the sum of its proper divisors (20073).

21813607 is a wasteful number, since it uses less digits than its factorization.

21813607 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20072.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 21813607 is about 4670.5039342666. The cubic root of 21813607 is about 279.4103535346.

The spelling of 21813607 in words is "twenty-one million, eight hundred thirteen thousand, six hundred seven".