21311799 has 4 divisors (see below), whose sum is σ = 28415736. Its totient is φ = 14207864.

The previous prime is 21311767. The next prime is 21311809. The reversal of 21311799 is 99711312.

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

It is a cyclic number.

It is not a de Polignac number, because 21311799 - 2⁵ = 21311767 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311729) 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, 3551964 + ... + 3551969.

It is an arithmetic number, because the mean of its divisors is an integer number (7103934).

Almost surely, 2^21311799 is an apocalyptic number.

21311799 is a deficient number, since it is larger than the sum of its proper divisors (7103937).

21311799 is an equidigital number, since it uses as much as digits as its factorization.

21311799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7103936.

The product of its digits is 3402, while the sum is 33.

The square root of 21311799 is about 4616.4704049739. The cubic root of 21311799 is about 277.2511591181.

The spelling of 21311799 in words is "twenty-one million, three hundred eleven thousand, seven hundred ninety-nine".