21724946 has 16 divisors (see below), whose sum is σ = 34980984. Its totient is φ = 10082304.

The previous prime is 21724943. The next prime is 21724991. The reversal of 21724946 is 64942712.

It can be written as a sum of positive squares in 4 ways, for example, as 21724921 + 25 = 4661^2 + 5^2 .

It is not an unprimeable number, because it can be changed into a prime (21724943) 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, 1895 + ... + 6858.

Almost surely, 2^21724946 is an apocalyptic number.

21724946 is a deficient number, since it is larger than the sum of its proper divisors (13256038).

21724946 is a wasteful number, since it uses less digits than its factorization.

21724946 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8845.

The product of its digits is 24192, while the sum is 35.

The square root of 21724946 is about 4661.0026818272. The cubic root of 21724946 is about 279.0312867712.

The spelling of 21724946 in words is "twenty-one million, seven hundred twenty-four thousand, nine hundred forty-six".