21913451 has 4 divisors (see below), whose sum is σ = 25043952. Its totient is φ = 18782952.

The previous prime is 21913439. The next prime is 21913453. The reversal of 21913451 is 15431912.

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 21913451 - 2⁶ = 21913387 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21913451.

It is not an unprimeable number, because it can be changed into a prime (21913453) 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, 1565240 + ... + 1565253.

It is an arithmetic number, because the mean of its divisors is an integer number (6260988).

Almost surely, 2^21913451 is an apocalyptic number.

21913451 is a deficient number, since it is larger than the sum of its proper divisors (3130501).

21913451 is an equidigital number, since it uses as much as digits as its factorization.

21913451 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3130500.

The product of its digits is 1080, while the sum is 26.

The square root of 21913451 is about 4681.1805135030. The cubic root of 21913451 is about 279.8360051581.

The spelling of 21913451 in words is "twenty-one million, nine hundred thirteen thousand, four hundred fifty-one".