21905225 has 12 divisors (see below), whose sum is σ = 27624720. Its totient is φ = 17226000.

The previous prime is 21905209. The next prime is 21905227. The reversal of 21905225 is 52250912.

It is not a de Polignac number, because 21905225 - 2⁴ = 21905209 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21905194 and 21905203.

It is not an unprimeable number, because it can be changed into a prime (21905227) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5951 + ... + 8900.

It is an arithmetic number, because the mean of its divisors is an integer number (2302060).

Almost surely, 2^21905225 is an apocalyptic number.

21905225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21905225 is a deficient number, since it is larger than the sum of its proper divisors (5719495).

21905225 is a wasteful number, since it uses less digits than its factorization.

21905225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14920 (or 14915 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21905225 is about 4680.3018065078. The cubic root of 21905225 is about 279.8009852811.

The spelling of 21905225 in words is "twenty-one million, nine hundred five thousand, two hundred twenty-five".