21455125 has 8 divisors (see below), whose sum is σ = 26776152. Its totient is φ = 17164000.

The previous prime is 21455117. The next prime is 21455143. The reversal of 21455125 is 52155412.

It can be written as a sum of positive squares in 4 ways, for example, as 2033476 + 19421649 = 1426^2 + 4407^2 .

It is not a de Polignac number, because 21455125 - 2³ = 21455117 is a prime.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21455125.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85696 + ... + 85945.

It is an arithmetic number, because the mean of its divisors is an integer number (3347019).

Almost surely, 2^21455125 is an apocalyptic number.

21455125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21455125 is a deficient number, since it is larger than the sum of its proper divisors (5321027).

21455125 is an equidigital number, since it uses as much as digits as its factorization.

21455125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171656 (or 171646 counting only the distinct ones).

The product of its digits is 2000, while the sum is 25.

The square root of 21455125 is about 4631.9677244126. The cubic root of 21455125 is about 277.8712936988.

The spelling of 21455125 in words is "twenty-one million, four hundred fifty-five thousand, one hundred twenty-five".