21172442 has 8 divisors (see below), whose sum is σ = 32783232. Its totient is φ = 10244700.

The previous prime is 21172439. The next prime is 21172451. The reversal of 21172442 is 24427112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 170684 + ... + 170807.

It is an arithmetic number, because the mean of its divisors is an integer number (4097904).

Almost surely, 2^21172442 is an apocalyptic number.

21172442 is a deficient number, since it is larger than the sum of its proper divisors (11610790).

21172442 is a wasteful number, since it uses less digits than its factorization.

21172442 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 341524.

The product of its digits is 896, while the sum is 23.

The square root of 21172442 is about 4601.3521925625. The cubic root of 21172442 is about 276.6455257148.

Adding to 21172442 its reverse (24427112), we get a palindrome (45599554).

The spelling of 21172442 in words is "twenty-one million, one hundred seventy-two thousand, four hundred forty-two".