21796987 has 4 divisors (see below), whose sum is σ = 21806560. Its totient is φ = 21787416.

The previous prime is 21796981. The next prime is 21797003. The reversal of 21796987 is 78969712.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21796987 - 2³ = 21796979 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 21796987.

It is not an unprimeable number, because it can be changed into a prime (21796981) 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 3 ways as a sum of consecutive naturals, for example, 814 + ... + 6652.

It is an arithmetic number, because the mean of its divisors is an integer number (5451640).

Almost surely, 2^21796987 is an apocalyptic number.

21796987 is a deficient number, since it is larger than the sum of its proper divisors (9573).

21796987 is an equidigital number, since it uses as much as digits as its factorization.

21796987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9572.

The product of its digits is 381024, while the sum is 49.

The square root of 21796987 is about 4668.7243439723. The cubic root of 21796987 is about 279.3393736799.

The spelling of 21796987 in words is "twenty-one million, seven hundred ninety-six thousand, nine hundred eighty-seven".