21230725 has 12 divisors (see below), whose sum is σ = 27471456. Its totient is φ = 16245680.

The previous prime is 21230719. The next prime is 21230749. The reversal of 21230725 is 52703212.

It is not a de Polignac number, because 21230725 - 2⁷ = 21230597 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21230696 and 21230705.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17887 + ... + 19036.

It is an arithmetic number, because the mean of its divisors is an integer number (2289288).

Almost surely, 2^21230725 is an apocalyptic number.

21230725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21230725 is a deficient number, since it is larger than the sum of its proper divisors (6240731).

21230725 is a wasteful number, since it uses less digits than its factorization.

21230725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36956 (or 36951 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 21230725 is about 4607.6810870545. The cubic root of 21230725 is about 276.8991409056.

Adding to 21230725 its reverse (52703212), we get a palindrome (73933937).

The spelling of 21230725 in words is "twenty-one million, two hundred thirty thousand, seven hundred twenty-five".