21587025 has 24 divisors (see below), whose sum is σ = 37792224. Its totient is φ = 10835200.

The previous prime is 21587023. The next prime is 21587057. The reversal of 21587025 is 52078512.

It is not a de Polignac number, because 21587025 - 2¹ = 21587023 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21586983 and 21587001.

It is not an unprimeable number, because it can be changed into a prime (21587023) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7191 + ... + 9740.

It is an arithmetic number, because the mean of its divisors is an integer number (1574676).

Almost surely, 2^21587025 is an apocalyptic number.

21587025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21587025 is a deficient number, since it is larger than the sum of its proper divisors (16205199).

21587025 is a wasteful number, since it uses less digits than its factorization.

21587025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16961 (or 16956 counting only the distinct ones).

The product of its (nonzero) digits is 5600, while the sum is 30.

The square root of 21587025 is about 4646.1839180127. The cubic root of 21587025 is about 278.4395553149.

The spelling of 21587025 in words is "twenty-one million, five hundred eighty-seven thousand, twenty-five".