21551025 has 12 divisors (see below), whose sum is σ = 35631152. Its totient is φ = 11493840.

The previous prime is 21550939. The next prime is 21551039. The reversal of 21551025 is 52015512.

It is not a de Polignac number, because 21551025 - 2⁹ = 21550513 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21550992 and 21551010.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 143599 + ... + 143748.

Almost surely, 2^21551025 is an apocalyptic number.

21551025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21551025 is a deficient number, since it is larger than the sum of its proper divisors (14080127).

21551025 is a wasteful number, since it uses less digits than its factorization.

21551025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 287360 (or 287355 counting only the distinct ones).

The product of its (nonzero) digits is 500, while the sum is 21.

The square root of 21551025 is about 4642.3081543560. The cubic root of 21551025 is about 278.2846875753.

Adding to 21551025 its reverse (52015512), we get a palindrome (73566537).

The spelling of 21551025 in words is "twenty-one million, five hundred fifty-one thousand, twenty-five".