21596891 has 8 divisors (see below), whose sum is σ = 22042800. Its totient is φ = 21153760.

The previous prime is 21596857. The next prime is 21596903. The reversal of 21596891 is 19869512.

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 21596891 - 2¹⁰ = 21595867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21596821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22481 + ... + 23421.

It is an arithmetic number, because the mean of its divisors is an integer number (2755350).

Almost surely, 2^21596891 is an apocalyptic number.

21596891 is a deficient number, since it is larger than the sum of its proper divisors (445909).

21596891 is an equidigital number, since it uses as much as digits as its factorization.

21596891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1389.

The product of its digits is 38880, while the sum is 41.

The square root of 21596891 is about 4647.2455282673. The cubic root of 21596891 is about 278.4819676167.

The spelling of 21596891 in words is "twenty-one million, five hundred ninety-six thousand, eight hundred ninety-one".