21744738 has 24 divisors (see below), whose sum is σ = 48117888. Its totient is φ = 7093752.

The previous prime is 21744727. The next prime is 21744739. The reversal of 21744738 is 83744712.

It is a happy number.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21744739) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 12006 + ... + 13697.

It is an arithmetic number, because the mean of its divisors is an integer number (2004912).

Almost surely, 2^21744738 is an apocalyptic number.

21744738 is an abundant number, since it is smaller than the sum of its proper divisors (26373150).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21744738 is a wasteful number, since it uses less digits than its factorization.

21744738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25758 (or 25755 counting only the distinct ones).

The product of its digits is 37632, while the sum is 36.

The square root of 21744738 is about 4663.1253468034. The cubic root of 21744738 is about 279.1159960113.

The spelling of 21744738 in words is "twenty-one million, seven hundred forty-four thousand, seven hundred thirty-eight".