21670025 has 36 divisors (see below), whose sum is σ = 30498048. Its totient is φ = 15238080.

The previous prime is 21670009. The next prime is 21670031. The reversal of 21670025 is 52007612.

21670025 = 106² + 107² + ... + 404².

It is not a de Polignac number, because 21670025 - 2⁴ = 21670009 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (23).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 97064 + ... + 97286.

It is an arithmetic number, because the mean of its divisors is an integer number (847168).

Almost surely, 2^21670025 is an apocalyptic number.

21670025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21670025 is a deficient number, since it is larger than the sum of its proper divisors (8828023).

21670025 is a wasteful number, since it uses less digits than its factorization.

21670025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 282 (or 264 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 21670025 is about 4655.1074101464. The cubic root of 21670025 is about 278.7959565484.

Adding to 21670025 its reverse (52007612), we get a palindrome (73677637).

The spelling of 21670025 in words is "twenty-one million, six hundred seventy thousand, twenty-five".