21431125 has 8 divisors (see below), whose sum is σ = 26746200. Its totient is φ = 17144800.

The previous prime is 21431119. The next prime is 21431129. The reversal of 21431125 is 52113412.

It can be written as a sum of positive squares in 4 ways, for example, as 142129 + 21288996 = 377^2 + 4614^2 .

It is not a de Polignac number, because 21431125 - 2²¹ = 19333973 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21431129) by changing a digit.

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, 85600 + ... + 85849.

It is an arithmetic number, because the mean of its divisors is an integer number (3343275).

Almost surely, 2^21431125 is an apocalyptic number.

21431125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21431125 is a deficient number, since it is larger than the sum of its proper divisors (5315075).

21431125 is an equidigital number, since it uses as much as digits as its factorization.

21431125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 171464 (or 171454 counting only the distinct ones).

The product of its digits is 240, while the sum is 19.

The square root of 21431125 is about 4629.3763078842. The cubic root of 21431125 is about 277.7676448156.

Adding to 21431125 its reverse (52113412), we get a palindrome (73544537).

The spelling of 21431125 in words is "twenty-one million, four hundred thirty-one thousand, one hundred twenty-five".