21003899 has 12 divisors (see below), whose sum is σ = 25496784. Its totient is φ = 17219664.

The previous prime is 21003893. The next prime is 21003929. The reversal of 21003899 is 99830012.

It is not a de Polignac number, because 21003899 - 2⁴ = 21003883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21003893) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8192 + ... + 10445.

It is an arithmetic number, because the mean of its divisors is an integer number (2124732).

Almost surely, 2^21003899 is an apocalyptic number.

21003899 is a deficient number, since it is larger than the sum of its proper divisors (4492885).

21003899 is a wasteful number, since it uses less digits than its factorization.

21003899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18674 (or 18667 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 21003899 is about 4583.0010909883. The cubic root of 21003899 is about 275.9094912567.

The spelling of 21003899 in words is "twenty-one million, three thousand, eight hundred ninety-nine".