21423925 has 48 divisors (see below), whose sum is σ = 30533760. Its totient is φ = 14826240.

The previous prime is 21423917. The next prime is 21423959. The reversal of 21423925 is 52932412.

It is not a de Polignac number, because 21423925 - 2³ = 21423917 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21423893 and 21423902.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 404199 + ... + 404251.

It is an arithmetic number, because the mean of its divisors is an integer number (636120).

Almost surely, 2^21423925 is an apocalyptic number.

21423925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21423925 is a deficient number, since it is larger than the sum of its proper divisors (9109835).

21423925 is a wasteful number, since it uses less digits than its factorization.

21423925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142 (or 137 counting only the distinct ones).

The product of its digits is 4320, while the sum is 28.

The square root of 21423925 is about 4628.5986000084. The cubic root of 21423925 is about 277.7365350620.

The spelling of 21423925 in words is "twenty-one million, four hundred twenty-three thousand, nine hundred twenty-five".