21311039 has 4 divisors (see below), whose sum is σ = 21320400. Its totient is φ = 21301680.

The previous prime is 21311033. The next prime is 21311051. The reversal of 21311039 is 93011312.

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 a de Polignac number, because none of the positive numbers 2^k-21311039 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21311039.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21311033) 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, 1187 + ... + 6635.

It is an arithmetic number, because the mean of its divisors is an integer number (5330100).

Almost surely, 2^21311039 is an apocalyptic number.

21311039 is a deficient number, since it is larger than the sum of its proper divisors (9361).

21311039 is an equidigital number, since it uses as much as digits as its factorization.

21311039 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9360.

The product of its (nonzero) digits is 162, while the sum is 20.

The square root of 21311039 is about 4616.3880902714. The cubic root of 21311039 is about 277.2478633947.

The spelling of 21311039 in words is "twenty-one million, three hundred eleven thousand, thirty-nine".