21724970 has 8 divisors (see below), whose sum is σ = 39104964. Its totient is φ = 8689984.

The previous prime is 21724943. The next prime is 21724991. The reversal of 21724970 is 7942712.

It can be written as a sum of positive squares in 2 ways, for example, as 21724921 + 49 = 4661^2 + 7^2 .

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, 1086239 + ... + 1086258.

Almost surely, 2^21724970 is an apocalyptic number.

21724970 is a deficient number, since it is larger than the sum of its proper divisors (17379994).

21724970 is a wasteful number, since it uses less digits than its factorization.

21724970 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2172504.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 21724970 is about 4661.0052563798. The cubic root of 21724970 is about 279.0313895217.

The spelling of 21724970 in words is "twenty-one million, seven hundred twenty-four thousand, nine hundred seventy".