21596649 has 4 divisors (see below), whose sum is σ = 28795536. Its totient is φ = 14397764.

The previous prime is 21596629. The next prime is 21596671. The reversal of 21596649 is 94669512.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21596649 - 2¹⁹ = 21072361 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21596649.

It is not an unprimeable number, because it can be changed into a prime (21596629) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3599439 + ... + 3599444.

It is an arithmetic number, because the mean of its divisors is an integer number (7198884).

Almost surely, 2^21596649 is an apocalyptic number.

It is an amenable number.

21596649 is a deficient number, since it is larger than the sum of its proper divisors (7198887).

21596649 is an equidigital number, since it uses as much as digits as its factorization.

21596649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7198886.

The product of its digits is 116640, while the sum is 42.

The square root of 21596649 is about 4647.2194912657. The cubic root of 21596649 is about 278.4809274533.

The spelling of 21596649 in words is "twenty-one million, five hundred ninety-six thousand, six hundred forty-nine".