21232131 has 4 divisors (see below), whose sum is σ = 28309512. Its totient is φ = 14154752.

The previous prime is 21232121. The next prime is 21232157. The reversal of 21232131 is 13123212.

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

It is a cyclic number.

It is not a de Polignac number, because 21232131 - 2¹⁰ = 21231107 is a prime.

It is a super-2 number, since 2×21232131² = 901606773602322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21232131.

It is not an unprimeable number, because it can be changed into a prime (21232121) 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, 3538686 + ... + 3538691.

It is an arithmetic number, because the mean of its divisors is an integer number (7077378).

Almost surely, 2^21232131 is an apocalyptic number.

21232131 is a deficient number, since it is larger than the sum of its proper divisors (7077381).

21232131 is an equidigital number, since it uses as much as digits as its factorization.

21232131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7077380.

The product of its digits is 72, while the sum is 15.

The square root of 21232131 is about 4607.8336558517. The cubic root of 21232131 is about 276.9052532985.

Adding to 21232131 its reverse (13123212), we get a palindrome (34355343).

The spelling of 21232131 in words is "twenty-one million, two hundred thirty-two thousand, one hundred thirty-one".