21430172 has 24 divisors (see below), whose sum is σ = 38539200. Its totient is φ = 10423296.

The previous prime is 21430169. The next prime is 21430177. The reversal of 21430172 is 27103412.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21430177) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22604 + ... + 23532.

It is an arithmetic number, because the mean of its divisors is an integer number (1605800).

Almost surely, 2^21430172 is an apocalyptic number.

It is an amenable number.

21430172 is a deficient number, since it is larger than the sum of its proper divisors (17109028).

21430172 is a wasteful number, since it uses less digits than its factorization.

21430172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085 (or 1083 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 21430172 is about 4629.2733771079. The cubic root of 21430172 is about 277.7635274941.

Adding to 21430172 its reverse (27103412), we get a palindrome (48533584).

The spelling of 21430172 in words is "twenty-one million, four hundred thirty thousand, one hundred seventy-two".