21563525 has 6 divisors (see below), whose sum is σ = 26738802. Its totient is φ = 17250800.

The previous prime is 21563519. The next prime is 21563539. The reversal of 21563525 is 52536512.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 1214404 + 20349121 = 1102^2 + 4511^2 .

It is not a de Polignac number, because 21563525 - 2¹⁰ = 21562501 is a prime.

It is a super-2 number, since 2×21563525² = 929971220851250, which contains 22 as substring.

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 5 ways as a sum of consecutive naturals, for example, 431246 + ... + 431295.

It is an arithmetic number, because the mean of its divisors is an integer number (4456467).

Almost surely, 2^21563525 is an apocalyptic number.

21563525 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21563525 is a deficient number, since it is larger than the sum of its proper divisors (5175277).

21563525 is an equidigital number, since it uses as much as digits as its factorization.

21563525 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862551 (or 862546 counting only the distinct ones).

The product of its digits is 9000, while the sum is 29.

The square root of 21563525 is about 4643.6542722300. The cubic root of 21563525 is about 278.3384806280.

The spelling of 21563525 in words is "twenty-one million, five hundred sixty-three thousand, five hundred twenty-five".