21891455 has 8 divisors (see below), whose sum is σ = 26316672. Its totient is φ = 17481888.

The previous prime is 21891449. The next prime is 21891473. The reversal of 21891455 is 55419812.

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

It is a cyclic number.

It is not a de Polignac number, because 21891455 - 2⁶ = 21891391 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 572 + ... + 6641.

It is an arithmetic number, because the mean of its divisors is an integer number (3289584).

Almost surely, 2^21891455 is an apocalyptic number.

21891455 is a deficient number, since it is larger than the sum of its proper divisors (4425217).

21891455 is an equidigital number, since it uses as much as digits as its factorization.

21891455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7825.

The product of its digits is 14400, while the sum is 35.

The square root of 21891455 is about 4678.8305162722. The cubic root of 21891455 is about 279.7423437595.

The spelling of 21891455 in words is "twenty-one million, eight hundred ninety-one thousand, four hundred fifty-five".