21905025 has 24 divisors (see below), whose sum is σ = 36601824. Its totient is φ = 11558400.

The previous prime is 21905011. The next prime is 21905053. The reversal of 21905025 is 52050912.

It is not a de Polignac number, because 21905025 - 2²³ = 13516417 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21904986 and 21905004.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5770 + ... + 8780.

It is an arithmetic number, because the mean of its divisors is an integer number (1525076).

Almost surely, 2^21905025 is an apocalyptic number.

21905025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21905025 is a deficient number, since it is larger than the sum of its proper divisors (14696799).

21905025 is a wasteful number, since it uses less digits than its factorization.

21905025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3121 (or 3116 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 24.

The square root of 21905025 is about 4680.2804403155. The cubic root of 21905025 is about 279.8001337283.

Adding to 21905025 its reverse (52050912), we get a palindrome (73955937).

The spelling of 21905025 in words is "twenty-one million, nine hundred five thousand, twenty-five".