21724762 has 4 divisors (see below), whose sum is σ = 32587146. Its totient is φ = 10862380.

The previous prime is 21724757. The next prime is 21724783. The reversal of 21724762 is 26742712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 17648401 + 4076361 = 4201^2 + 2019^2 .

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5431189 + ... + 5431192.

Almost surely, 2^21724762 is an apocalyptic number.

21724762 is a deficient number, since it is larger than the sum of its proper divisors (10862384).

21724762 is a wasteful number, since it uses less digits than its factorization.

21724762 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10862383.

The product of its digits is 9408, while the sum is 31.

The square root of 21724762 is about 4660.9829435431. The cubic root of 21724762 is about 279.0304990147.

The spelling of 21724762 in words is "twenty-one million, seven hundred twenty-four thousand, seven hundred sixty-two".