21742625 has 24 divisors (see below), whose sum is σ = 28193256. Its totient is φ = 16740000.

The previous prime is 21742619. The next prime is 21742627. The reversal of 21742625 is 52624712.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 5997601 + 15745024 = 2449^2 + 3968^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21742625 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742627) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 120035 + ... + 120215.

It is an arithmetic number, because the mean of its divisors is an integer number (1174719).

Almost surely, 2^21742625 is an apocalyptic number.

21742625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21742625 is a deficient number, since it is larger than the sum of its proper divisors (6450631).

21742625 is an equidigital number, since it uses as much as digits as its factorization.

21742625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 258 (or 217 counting only the distinct ones).

The product of its digits is 6720, while the sum is 29.

The square root of 21742625 is about 4662.8987765123. The cubic root of 21742625 is about 279.1069548783.

The spelling of 21742625 in words is "twenty-one million, seven hundred forty-two thousand, six hundred twenty-five".