21497225 has 12 divisors (see below), whose sum is σ = 26831244. Its totient is φ = 17085120.

The previous prime is 21497213. The next prime is 21497257. The reversal of 21497225 is 52279412.

It can be written as a sum of positive squares in 6 ways, for example, as 364816 + 21132409 = 604^2 + 4597^2 .

It is not a de Polignac number, because 21497225 - 2¹⁴ = 21480841 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21497191 and 21497200.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1187 + ... + 6663.

It is an arithmetic number, because the mean of its divisors is an integer number (2235937).

Almost surely, 2^21497225 is an apocalyptic number.

21497225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21497225 is a deficient number, since it is larger than the sum of its proper divisors (5334019).

21497225 is a wasteful number, since it uses less digits than its factorization.

21497225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5644 (or 5639 counting only the distinct ones).

The product of its digits is 10080, while the sum is 32.

The square root of 21497225 is about 4636.5100021460. The cubic root of 21497225 is about 278.0529245545.

The spelling of 21497225 in words is "twenty-one million, four hundred ninety-seven thousand, two hundred twenty-five".