21297455 has 16 divisors (see below), whose sum is σ = 26611200. Its totient is φ = 16343040.

The previous prime is 21297431. The next prime is 21297457. The reversal of 21297455 is 55479212.

It is not a de Polignac number, because 21297455 - 2²⁴ = 4520239 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21297457) 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, 27311 + ... + 28079.

It is an arithmetic number, because the mean of its divisors is an integer number (1663200).

Almost surely, 2^21297455 is an apocalyptic number.

21297455 is a deficient number, since it is larger than the sum of its proper divisors (5313745).

21297455 is a wasteful number, since it uses less digits than its factorization.

21297455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 994.

The product of its digits is 25200, while the sum is 35.

The square root of 21297455 is about 4614.9165756273. The cubic root of 21297455 is about 277.1889434541.

The spelling of 21297455 in words is "twenty-one million, two hundred ninety-seven thousand, four hundred fifty-five".