21013131 has 8 divisors (see below), whose sum is σ = 28372480. Its totient is φ = 13831272.

The previous prime is 21013127. The next prime is 21013159. The reversal of 21013131 is 13131012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21013131 - 2² = 21013127 is a prime.

It is a super-2 number, since 2×21013131² = 883103348846322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21013631) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 44095 + ... + 44568.

It is an arithmetic number, because the mean of its divisors is an integer number (3546560).

Almost surely, 2^21013131 is an apocalyptic number.

21013131 is a deficient number, since it is larger than the sum of its proper divisors (7359349).

21013131 is an equidigital number, since it uses as much as digits as its factorization.

21013131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88745.

The product of its (nonzero) digits is 18, while the sum is 12.

The square root of 21013131 is about 4584.0081806210. The cubic root of 21013131 is about 275.9499095193.

Adding to 21013131 its reverse (13131012), we get a palindrome (34144143).

The spelling of 21013131 in words is "twenty-one million, thirteen thousand, one hundred thirty-one".