21172324 has 6 divisors (see below), whose sum is σ = 37051574. Its totient is φ = 10586160.

The previous prime is 21172309. The next prime is 21172331. The reversal of 21172324 is 42327112.

It can be written as a sum of positive squares in only one way, i.e., 11437924 + 9734400 = 3382^2 + 3120^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21172295 and 21172304.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2646537 + ... + 2646544.

Almost surely, 2^21172324 is an apocalyptic number.

It is an amenable number.

21172324 is a deficient number, since it is larger than the sum of its proper divisors (15879250).

21172324 is a wasteful number, since it uses less digits than its factorization.

21172324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5293085 (or 5293083 counting only the distinct ones).

The product of its digits is 672, while the sum is 22.

The square root of 21172324 is about 4601.3393702269. The cubic root of 21172324 is about 276.6450117726.

Adding to 21172324 its reverse (42327112), we get a palindrome (63499436).

The spelling of 21172324 in words is "twenty-one million, one hundred seventy-two thousand, three hundred twenty-four".