21140531 has 4 divisors (see below), whose sum is σ = 21175632. Its totient is φ = 21105432.

The previous prime is 21140513. The next prime is 21140549. The reversal of 21140531 is 13504112.

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

It is an interprime number because it is at equal distance from previous prime (21140513) and next prime (21140549).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21140531 is a prime.

It is a super-2 number, since 2×21140531² = 893844101923922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21140501) 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, 16631 + ... + 17856.

It is an arithmetic number, because the mean of its divisors is an integer number (5293908).

Almost surely, 2^21140531 is an apocalyptic number.

21140531 is a deficient number, since it is larger than the sum of its proper divisors (35101).

21140531 is an equidigital number, since it uses as much as digits as its factorization.

21140531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35100.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21140531 is about 4597.8833173538. The cubic root of 21140531 is about 276.5064695732.

Adding to 21140531 its reverse (13504112), we get a palindrome (34644643).

The spelling of 21140531 in words is "twenty-one million, one hundred forty thousand, five hundred thirty-one".