21298225 has 27 divisors (see below), whose sum is σ = 29006049. Its totient is φ = 15506400.

The previous prime is 21298217. The next prime is 21298241. The reversal of 21298225 is 52289212.

21298225 = 628² + 629² + ... + 677².

The square root of 21298225 is 4615.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 5489649 + 15808576 = 2343^2 + 3976^2 .

It is not a de Polignac number, because 21298225 - 2³ = 21298217 is a prime.

It is a super-2 number, since 2×21298225² = 907228776301250, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 299940 + ... + 300010.

Almost surely, 2^21298225 is an apocalyptic number.

21298225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21298225 is the 4615-th square number.

21298225 is the 2308-th centered octagonal number.

It is an amenable number.

21298225 is a deficient number, since it is larger than the sum of its proper divisors (7707824).

21298225 is an equidigital number, since it uses as much as digits as its factorization.

21298225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178 (or 89 counting only the distinct ones).

The product of its digits is 5760, while the sum is 31.

The cubic root of 21298225 is about 277.1922839614.

The spelling of 21298225 in words is "twenty-one million, two hundred ninety-eight thousand, two hundred twenty-five".