21899943 has 32 divisors (see below), whose sum is σ = 35777280. Its totient is φ = 13154400.

The previous prime is 21899939. The next prime is 21899987. The reversal of 21899943 is 34999812.

It is not a de Polignac number, because 21899943 - 2² = 21899939 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21899923) 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 31 ways as a sum of consecutive naturals, for example, 14368 + ... + 15818.

It is an arithmetic number, because the mean of its divisors is an integer number (1118040).

Almost surely, 2^21899943 is an apocalyptic number.

21899943 is a deficient number, since it is larger than the sum of its proper divisors (13877337).

21899943 is a wasteful number, since it uses less digits than its factorization.

21899943 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1516 (or 1510 counting only the distinct ones).

The product of its digits is 139968, while the sum is 45.

The square root of 21899943 is about 4679.7374926378. The cubic root of 21899943 is about 279.7784940321.

The spelling of 21899943 in words is "twenty-one million, eight hundred ninety-nine thousand, nine hundred forty-three".