21400242 has 16 divisors (see below), whose sum is σ = 43387680. Its totient is φ = 7035552.

The previous prime is 21400219. The next prime is 21400271. The reversal of 21400242 is 24200412.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23992 + ... + 24867.

It is an arithmetic number, because the mean of its divisors is an integer number (2711730).

Almost surely, 2^21400242 is an apocalyptic number.

21400242 is an abundant number, since it is smaller than the sum of its proper divisors (21987438).

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

21400242 is a wasteful number, since it uses less digits than its factorization.

21400242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 48937.

The product of its (nonzero) digits is 128, while the sum is 15.

The square root of 21400242 is about 4626.0395588451. The cubic root of 21400242 is about 277.6341563804.

Adding to 21400242 its reverse (24200412), we get a palindrome (45600654).

The spelling of 21400242 in words is "twenty-one million, four hundred thousand, two hundred forty-two".