21551125 has 16 divisors (see below), whose sum is σ = 27411696. Its totient is φ = 16910400.

The previous prime is 21551119. The next prime is 21551137. The reversal of 21551125 is 52115512.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 381924 + 21169201 = 618^2 + 4601^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21551125 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21551096 and 21551105.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4999 + ... + 8251.

It is an arithmetic number, because the mean of its divisors is an integer number (1713231).

Almost surely, 2^21551125 is an apocalyptic number.

21551125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21551125 is a deficient number, since it is larger than the sum of its proper divisors (5860571).

21551125 is an equidigital number, since it uses as much as digits as its factorization.

21551125 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3321 (or 3311 counting only the distinct ones).

The product of its digits is 500, while the sum is 22.

The square root of 21551125 is about 4642.3189248478. The cubic root of 21551125 is about 278.2851180023.

Adding to 21551125 its reverse (52115512), we get a palindrome (73666637).

The spelling of 21551125 in words is "twenty-one million, five hundred fifty-one thousand, one hundred twenty-five".