21331013 has 4 divisors (see below), whose sum is σ = 23270208. Its totient is φ = 19391820.

The previous prime is 21331001. The next prime is 21331021. The reversal of 21331013 is 31013312.

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 21331013 - 2⁶ = 21330949 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 (21331043) 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, 969581 + ... + 969602.

It is an arithmetic number, because the mean of its divisors is an integer number (5817552).

Almost surely, 2^21331013 is an apocalyptic number.

It is an amenable number.

21331013 is a deficient number, since it is larger than the sum of its proper divisors (1939195).

21331013 is a wasteful number, since it uses less digits than its factorization.

21331013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1939194.

The product of its (nonzero) digits is 54, while the sum is 14.

The square root of 21331013 is about 4618.5509632351. The cubic root of 21331013 is about 277.3344541927.

Adding to 21331013 its reverse (31013312), we get a palindrome (52344325).

The spelling of 21331013 in words is "twenty-one million, three hundred thirty-one thousand, thirteen".