21791648 has 12 divisors (see below), whose sum is σ = 42902370. Its totient is φ = 10895808.

The previous prime is 21791647. The next prime is 21791657. The reversal of 21791648 is 84619712.

It can be written as a sum of positive squares in only one way, i.e., 21641104 + 150544 = 4652^2 + 388^2 .

It is not an unprimeable number, because it can be changed into a prime (21791641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340463 + ... + 340526.

Almost surely, 2^21791648 is an apocalyptic number.

It is an amenable number.

21791648 is a deficient number, since it is larger than the sum of its proper divisors (21110722).

21791648 is an equidigital number, since it uses as much as digits as its factorization.

21791648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 680999 (or 680991 counting only the distinct ones).

The product of its digits is 24192, while the sum is 38.

The square root of 21791648 is about 4668.1525253573. The cubic root of 21791648 is about 279.3165644923.

The spelling of 21791648 in words is "twenty-one million, seven hundred ninety-one thousand, six hundred forty-eight".