21099425 has 12 divisors (see below), whose sum is σ = 26534016. Its totient is φ = 16640400.

The previous prime is 21099413. The next prime is 21099427. The reversal of 21099425 is 52499012.

It is not a de Polignac number, because 21099425 - 2¹⁰ = 21098401 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21099391 and 21099400.

It is not an unprimeable number, because it can be changed into a prime (21099427) 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, 4169 + ... + 7718.

It is an arithmetic number, because the mean of its divisors is an integer number (2211168).

Almost surely, 2^21099425 is an apocalyptic number.

21099425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21099425 is a deficient number, since it is larger than the sum of its proper divisors (5434591).

21099425 is a wasteful number, since it uses less digits than its factorization.

21099425 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11968 (or 11963 counting only the distinct ones).

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 21099425 is about 4593.4110419165. The cubic root of 21099425 is about 276.3271386992.

The spelling of 21099425 in words is "twenty-one million, ninety-nine thousand, four hundred twenty-five".