21647649 has 8 divisors (see below), whose sum is σ = 28887840. Its totient is φ = 14419616.

The previous prime is 21647629. The next prime is 21647653. The reversal of 21647649 is 94674612.

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 21647649 - 2⁵ = 21647617 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21647609) 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, 2629 + ... + 7085.

It is an arithmetic number, because the mean of its divisors is an integer number (3610980).

Almost surely, 2^21647649 is an apocalyptic number.

It is an amenable number.

21647649 is a deficient number, since it is larger than the sum of its proper divisors (7240191).

21647649 is a wasteful number, since it uses less digits than its factorization.

21647649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6079.

The product of its digits is 72576, while the sum is 39.

The square root of 21647649 is about 4652.7034076975. The cubic root of 21647649 is about 278.6999639389.

The spelling of 21647649 in words is "twenty-one million, six hundred forty-seven thousand, six hundred forty-nine".