21132251 has 8 divisors (see below), whose sum is σ = 24199680. Its totient is φ = 18076968.

The previous prime is 21132233. The next prime is 21132257. The reversal of 21132251 is 15223112.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-21132251 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21132257) 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, 1070 + ... + 6588.

It is an arithmetic number, because the mean of its divisors is an integer number (3024960).

Almost surely, 2^21132251 is an apocalyptic number.

21132251 is a deficient number, since it is larger than the sum of its proper divisors (3067429).

21132251 is an equidigital number, since it uses as much as digits as its factorization.

21132251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6073.

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

The square root of 21132251 is about 4596.9828148471. The cubic root of 21132251 is about 276.4703655836.

Adding to 21132251 its reverse (15223112), we get a palindrome (36355363).

The spelling of 21132251 in words is "twenty-one million, one hundred thirty-two thousand, two hundred fifty-one".