21911867 has 4 divisors (see below), whose sum is σ = 21923880. Its totient is φ = 21899856.

The previous prime is 21911839. The next prime is 21911887. The reversal of 21911867 is 76811912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21911867 - 2⁶ = 21911803 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21911837) 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, 2642 + ... + 7127.

It is an arithmetic number, because the mean of its divisors is an integer number (5480970).

Almost surely, 2^21911867 is an apocalyptic number.

21911867 is a deficient number, since it is larger than the sum of its proper divisors (12013).

21911867 is an equidigital number, since it uses as much as digits as its factorization.

21911867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12012.

The product of its digits is 6048, while the sum is 35.

The square root of 21911867 is about 4681.0113223533. The cubic root of 21911867 is about 279.8292624059.

The spelling of 21911867 in words is "twenty-one million, nine hundred eleven thousand, eight hundred sixty-seven".