21501025 has 36 divisors (see below), whose sum is σ = 33039552. Its totient is φ = 13590720.

The previous prime is 21501023. The next prime is 21501031. The reversal of 21501025 is 52010512.

It is not a de Polignac number, because 21501025 - 2¹ = 21501023 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21501023) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 29212 + ... + 29938.

Almost surely, 2^21501025 is an apocalyptic number.

21501025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21501025 is a deficient number, since it is larger than the sum of its proper divisors (11538527).

21501025 is a wasteful number, since it uses less digits than its factorization.

21501025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 770 (or 752 counting only the distinct ones).

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 21501025 is about 4636.9197750231. The cubic root of 21501025 is about 278.0693071165.

Adding to 21501025 its reverse (52010512), we get a palindrome (73511537).

The spelling of 21501025 in words is "twenty-one million, five hundred one thousand, twenty-five".