21727744 has 20 divisors (see below), whose sum is σ = 43414074. Its totient is φ = 10863616.

The previous prime is 21727723. The next prime is 21727777. The reversal of 21727744 is 44772712.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 10969344 + 10758400 = 3312^2 + 3280^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20707 + ... + 21730.

Almost surely, 2^21727744 is an apocalyptic number.

It is an amenable number.

21727744 is a deficient number, since it is larger than the sum of its proper divisors (21686330).

21727744 is an frugal number, since it uses more digits than its factorization.

21727744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42455 (or 42439 counting only the distinct ones).

The product of its digits is 21952, while the sum is 34.

The square root of 21727744 is about 4661.3028221732. The cubic root of 21727744 is about 279.0432652593.

The spelling of 21727744 in words is "twenty-one million, seven hundred twenty-seven thousand, seven hundred forty-four".