21983851 has 4 divisors (see below), whose sum is σ = 22344304. Its totient is φ = 21623400.

The previous prime is 21983807. The next prime is 21983861. The reversal of 21983851 is 15838912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21983851 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 21983851.

It is not an unprimeable number, because it can be changed into a prime (21983861) 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, 180135 + ... + 180256.

It is an arithmetic number, because the mean of its divisors is an integer number (5586076).

Almost surely, 2^21983851 is an apocalyptic number.

21983851 is a deficient number, since it is larger than the sum of its proper divisors (360453).

21983851 is an equidigital number, since it uses as much as digits as its factorization.

21983851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 360452.

The product of its digits is 17280, while the sum is 37.

The square root of 21983851 is about 4688.6939546104. The cubic root of 21983851 is about 280.1353554753.

The spelling of 21983851 in words is "twenty-one million, nine hundred eighty-three thousand, eight hundred fifty-one".