21242142 has 16 divisors (see below), whose sum is σ = 47204880. Its totient is φ = 7080696.

The previous prime is 21242131. The next prime is 21242153. The reversal of 21242142 is 24124212.

It is an interprime number because it is at equal distance from previous prime (21242131) and next prime (21242153).

It is a Harshad number since it is a multiple of its sum of digits (18).

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, 196633 + ... + 196740.

It is an arithmetic number, because the mean of its divisors is an integer number (2950305).

It is a self-describing number.

Almost surely, 2^21242142 is an apocalyptic number.

21242142 is an abundant number, since it is smaller than the sum of its proper divisors (25962738).

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

21242142 is a wasteful number, since it uses less digits than its factorization.

21242142 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 393384 (or 393378 counting only the distinct ones).

The product of its digits is 256, while the sum is 18.

The square root of 21242142 is about 4608.9198300686. The cubic root of 21242142 is about 276.9487669543.

Adding to 21242142 its reverse (24124212), we get a palindrome (45366354).

The spelling of 21242142 in words is "twenty-one million, two hundred forty-two thousand, one hundred forty-two".