21513325 has 6 divisors (see below), whose sum is σ = 26676554. Its totient is φ = 17210640.

The previous prime is 21513307. The next prime is 21513329. The reversal of 21513325 is 52331512.

It can be written as a sum of positive squares in 3 ways, for example, as 252004 + 21261321 = 502^2 + 4611^2 .

It is not a de Polignac number, because 21513325 - 2⁷ = 21513197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21513296 and 21513305.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513329) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 430242 + ... + 430291.

Almost surely, 2^21513325 is an apocalyptic number.

21513325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21513325 is a deficient number, since it is larger than the sum of its proper divisors (5163229).

21513325 is an equidigital number, since it uses as much as digits as its factorization.

21513325 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 860543 (or 860538 counting only the distinct ones).

The product of its digits is 900, while the sum is 22.

The square root of 21513325 is about 4638.2458968882. The cubic root of 21513325 is about 278.1223216508.

Adding to 21513325 its reverse (52331512), we get a palindrome (73844837).

It can be divided in two parts, 2151 and 3325, that added together give a square (5476 = 74²).

The spelling of 21513325 in words is "twenty-one million, five hundred thirteen thousand, three hundred twenty-five".