21493242 has 16 divisors (see below), whose sum is σ = 47762880. Its totient is φ = 7164396.

The previous prime is 21493231. The next prime is 21493243. The reversal of 21493242 is 24239412.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21493243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198958 + ... + 199065.

It is an arithmetic number, because the mean of its divisors is an integer number (2985180).

Almost surely, 2^21493242 is an apocalyptic number.

21493242 is an abundant number, since it is smaller than the sum of its proper divisors (26269638).

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

21493242 is a wasteful number, since it uses less digits than its factorization.

21493242 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398034 (or 398028 counting only the distinct ones).

The product of its digits is 3456, while the sum is 27.

The square root of 21493242 is about 4636.0804565926. The cubic root of 21493242 is about 278.0357509704.

The spelling of 21493242 in words is "twenty-one million, four hundred ninety-three thousand, two hundred forty-two".