21108542 has 16 divisors (see below), whose sum is σ = 38969952. Its totient is φ = 8350560.

The previous prime is 21108541. The next prime is 21108553. The reversal of 21108542 is 24580112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21108541) 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, 57809 + ... + 58172.

It is an arithmetic number, because the mean of its divisors is an integer number (2435622).

Almost surely, 2^21108542 is an apocalyptic number.

21108542 is a deficient number, since it is larger than the sum of its proper divisors (17861410).

21108542 is a wasteful number, since it uses less digits than its factorization.

21108542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 116003.

The product of its (nonzero) digits is 640, while the sum is 23.

The square root of 21108542 is about 4594.4033344930. The cubic root of 21108542 is about 276.3669330183.

Adding to 21108542 its reverse (24580112), we get a palindrome (45688654).

The spelling of 21108542 in words is "twenty-one million, one hundred eight thousand, five hundred forty-two".