21112451 has 4 divisors (see below), whose sum is σ = 21122592. Its totient is φ = 21102312.

The previous prime is 21112433. The next prime is 21112547. The reversal of 21112451 is 15421112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112451 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21112411) 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, 680 + ... + 6533.

It is an arithmetic number, because the mean of its divisors is an integer number (5280648).

Almost surely, 2^21112451 is an apocalyptic number.

21112451 is a deficient number, since it is larger than the sum of its proper divisors (10141).

21112451 is an equidigital number, since it uses as much as digits as its factorization.

21112451 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10140.

The product of its digits is 80, while the sum is 17.

The square root of 21112451 is about 4594.8287236849. The cubic root of 21112451 is about 276.3839916994.

Adding to 21112451 its reverse (15421112), we get a palindrome (36533563).

The spelling of 21112451 in words is "twenty-one million, one hundred twelve thousand, four hundred fifty-one".