21455351 has 4 divisors (see below), whose sum is σ = 22584600. Its totient is φ = 20326104.

The previous prime is 21455327. The next prime is 21455353. The reversal of 21455351 is 15355412.

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 21455351 - 2²² = 17261047 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 21455351.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21455353) 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, 564596 + ... + 564633.

It is an arithmetic number, because the mean of its divisors is an integer number (5646150).

Almost surely, 2^21455351 is an apocalyptic number.

21455351 is a deficient number, since it is larger than the sum of its proper divisors (1129249).

21455351 is a wasteful number, since it uses less digits than its factorization.

21455351 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1129248.

The product of its digits is 3000, while the sum is 26.

The square root of 21455351 is about 4631.9921200278. The cubic root of 21455351 is about 277.8722693584.

The spelling of 21455351 in words is "twenty-one million, four hundred fifty-five thousand, three hundred fifty-one".