21789542 has 8 divisors (see below), whose sum is σ = 34404600. Its totient is φ = 10321344.

The previous prime is 21789511. The next prime is 21789557. The reversal of 21789542 is 24598712.

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

It is a Harshad number since it is a multiple of its sum of digits (38), and also a Moran number because the ratio is a prime number: 573409 = 21789542 / (2 + 1 + 7 + 8 + 9 + 5 + 4 + 2).

It is a junction number, because it is equal to n+sod(n) for n = 21789496 and 21789505.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 286667 + ... + 286742.

It is an arithmetic number, because the mean of its divisors is an integer number (4300575).

Almost surely, 2^21789542 is an apocalyptic number.

21789542 is a deficient number, since it is larger than the sum of its proper divisors (12615058).

21789542 is a wasteful number, since it uses less digits than its factorization.

21789542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 573430.

The product of its digits is 40320, while the sum is 38.

The square root of 21789542 is about 4667.9269488714. The cubic root of 21789542 is about 279.3075662492.

The spelling of 21789542 in words is "twenty-one million, seven hundred eighty-nine thousand, five hundred forty-two".