21667013 has 4 divisors (see below), whose sum is σ = 21686688. Its totient is φ = 21647340.

The previous prime is 21667003. The next prime is 21667021. The reversal of 21667013 is 31076612.

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 21667013 - 2⁶ = 21666949 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 (21667003) 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, 8081 + ... + 10422.

It is an arithmetic number, because the mean of its divisors is an integer number (5421672).

Almost surely, 2^21667013 is an apocalyptic number.

It is an amenable number.

21667013 is a deficient number, since it is larger than the sum of its proper divisors (19675).

21667013 is a wasteful number, since it uses less digits than its factorization.

21667013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19674.

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 21667013 is about 4654.7838832754. The cubic root of 21667013 is about 278.7830389764.

The spelling of 21667013 in words is "twenty-one million, six hundred sixty-seven thousand, thirteen".