21504142 has 16 divisors (see below), whose sum is σ = 36324864. Its totient is φ = 9459000.

The previous prime is 21504137. The next prime is 21504151. The reversal of 21504142 is 24140512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15084 + ... + 16447.

It is an arithmetic number, because the mean of its divisors is an integer number (2270304).

Almost surely, 2^21504142 is an apocalyptic number.

21504142 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21504142 is a deficient number, since it is larger than the sum of its proper divisors (14820722).

21504142 is a wasteful number, since it uses less digits than its factorization.

21504142 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31575.

The product of its (nonzero) digits is 320, while the sum is 19.

The square root of 21504142 is about 4637.2558695849. The cubic root of 21504142 is about 278.0827436875.

Adding to 21504142 its reverse (24140512), we get a palindrome (45644654).

The spelling of 21504142 in words is "twenty-one million, five hundred four thousand, one hundred forty-two".