21311451 has 16 divisors (see below), whose sum is σ = 36083200. Its totient is φ = 12177864.

The previous prime is 21311447. The next prime is 21311453. The reversal of 21311451 is 15411312.

21311451 is a `hidden beast` number, since 213 + 1 + 1 + 451 = 666.

It is not a de Polignac number, because 21311451 - 2² = 21311447 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311453) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56191 + ... + 56568.

It is an arithmetic number, because the mean of its divisors is an integer number (2255200).

Almost surely, 2^21311451 is an apocalyptic number.

21311451 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21311451 is a deficient number, since it is larger than the sum of its proper divisors (14771749).

21311451 is a wasteful number, since it uses less digits than its factorization.

21311451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112775 (or 112769 counting only the distinct ones).

The product of its digits is 120, while the sum is 18.

The square root of 21311451 is about 4616.4327136871. The cubic root of 21311451 is about 277.2496500335.

Adding to 21311451 its reverse (15411312), we get a palindrome (36722763).

It can be divided in two parts, 213 and 11451, that added together give a square (11664 = 108²).

The spelling of 21311451 in words is "twenty-one million, three hundred eleven thousand, four hundred fifty-one".