21742459 has 8 divisors (see below), whose sum is σ = 22170560. Its totient is φ = 21318336.

The previous prime is 21742451. The next prime is 21742471. The reversal of 21742459 is 95424712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21742459 - 2³ = 21742451 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21742451) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11527 + ... + 13279.

It is an arithmetic number, because the mean of its divisors is an integer number (2771320).

Almost surely, 2^21742459 is an apocalyptic number.

21742459 is a deficient number, since it is larger than the sum of its proper divisors (428101).

21742459 is a wasteful number, since it uses less digits than its factorization.

21742459 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1989.

The product of its digits is 20160, while the sum is 34.

The square root of 21742459 is about 4662.8809763922. The cubic root of 21742459 is about 279.1062445704.

It can be divided in two parts, 21742 and 459, that added together give a square (22201 = 149²).

The spelling of 21742459 in words is "twenty-one million, seven hundred forty-two thousand, four hundred fifty-nine".