21889851 has 4 divisors (see below), whose sum is σ = 29186472. Its totient is φ = 14593232.

The previous prime is 21889841. The next prime is 21889871. The reversal of 21889851 is 15898812.

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

It is a cyclic number.

It is not a de Polignac number, because 21889851 - 2⁶ = 21889787 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21889811) 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, 3648306 + ... + 3648311.

It is an arithmetic number, because the mean of its divisors is an integer number (7296618).

Almost surely, 2^21889851 is an apocalyptic number.

21889851 is a deficient number, since it is larger than the sum of its proper divisors (7296621).

21889851 is an equidigital number, since it uses as much as digits as its factorization.

21889851 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7296620.

The product of its digits is 46080, while the sum is 42.

The square root of 21889851 is about 4678.6591027772. The cubic root of 21889851 is about 279.7355112964.

The spelling of 21889851 in words is "twenty-one million, eight hundred eighty-nine thousand, eight hundred fifty-one".