21371911 has 4 divisors (see below), whose sum is σ = 23314824. Its totient is φ = 19429000.

The previous prime is 21371893. The next prime is 21371929. The reversal of 21371911 is 11917312.

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

It is an interprime number because it is at equal distance from previous prime (21371893) and next prime (21371929).

It is a cyclic number.

It is not a de Polignac number, because 21371911 - 2¹⁹ = 20847623 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 (21371971) 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, 971440 + ... + 971461.

It is an arithmetic number, because the mean of its divisors is an integer number (5828706).

Almost surely, 2^21371911 is an apocalyptic number.

21371911 is a deficient number, since it is larger than the sum of its proper divisors (1942913).

21371911 is a wasteful number, since it uses less digits than its factorization.

21371911 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1942912.

The product of its digits is 378, while the sum is 25.

The square root of 21371911 is about 4622.9764221765. The cubic root of 21371911 is about 277.5115856971.

The spelling of 21371911 in words is "twenty-one million, three hundred seventy-one thousand, nine hundred eleven".