21561042 has 8 divisors (see below), whose sum is σ = 43122096. Its totient is φ = 7187012.

The previous prime is 21561041. The next prime is 21561077. The reversal of 21561042 is 24016512.

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

21561042 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21561041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1796748 + ... + 1796759.

It is an arithmetic number, because the mean of its divisors is an integer number (5390262).

Almost surely, 2^21561042 is an apocalyptic number.

21561042 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21561042 is a wasteful number, since it uses less digits than its factorization.

21561042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3593512.

The product of its (nonzero) digits is 480, while the sum is 21.

The square root of 21561042 is about 4643.3869104351. The cubic root of 21561042 is about 278.3277968309.

Adding to 21561042 its reverse (24016512), we get a palindrome (45577554).

The spelling of 21561042 in words is "twenty-one million, five hundred sixty-one thousand, forty-two".