21648961 has 8 divisors (see below), whose sum is σ = 23163200. Its totient is φ = 20172240.

The previous prime is 21648947. The next prime is 21648997. The reversal of 21648961 is 16984612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21648961 - 2¹¹ = 21646913 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21648961.

It is not an unprimeable number, because it can be changed into a prime (21648901) 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, 8181 + ... + 10498.

It is an arithmetic number, because the mean of its divisors is an integer number (2895400).

Almost surely, 2^21648961 is an apocalyptic number.

It is an amenable number.

21648961 is a deficient number, since it is larger than the sum of its proper divisors (1514239).

21648961 is a wasteful number, since it uses less digits than its factorization.

21648961 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18759.

The product of its digits is 20736, while the sum is 37.

The square root of 21648961 is about 4652.8443988597. The cubic root of 21648961 is about 278.7055942187.

The spelling of 21648961 in words is "twenty-one million, six hundred forty-eight thousand, nine hundred sixty-one".