21103131 has 8 divisors (see below), whose sum is σ = 32157184. Its totient is φ = 12058920.

The previous prime is 21103127. The next prime is 21103139. The reversal of 21103131 is 13130112.

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

It is not a de Polignac number, because 21103131 - 2² = 21103127 is a prime.

It is a super-2 number, since 2×21103131² = 890684276006322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21103139) 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, 502435 + ... + 502476.

It is an arithmetic number, because the mean of its divisors is an integer number (4019648).

Almost surely, 2^21103131 is an apocalyptic number.

21103131 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21103131 is a deficient number, since it is larger than the sum of its proper divisors (11054053).

21103131 is a wasteful number, since it uses less digits than its factorization.

21103131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1004921.

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

The square root of 21103131 is about 4593.8144281196. The cubic root of 21103131 is about 276.3433162084.

Adding to 21103131 its reverse (13130112), we get a palindrome (34233243).

The spelling of 21103131 in words is "twenty-one million, one hundred three thousand, one hundred thirty-one".