21988211 has 12 divisors (see below), whose sum is σ = 25744392. Its totient is φ = 18724608.

The previous prime is 21988199. The next prime is 21988229. The reversal of 21988211 is 11288912.

It is not a de Polignac number, because 21988211 - 2⁶ = 21988147 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21988231) 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, 6611 + ... + 9363.

It is an arithmetic number, because the mean of its divisors is an integer number (2145366).

Almost surely, 2^21988211 is an apocalyptic number.

21988211 is a deficient number, since it is larger than the sum of its proper divisors (3756181).

21988211 is a wasteful number, since it uses less digits than its factorization.

21988211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2930 (or 2923 counting only the distinct ones).

The product of its digits is 2304, while the sum is 32.

The square root of 21988211 is about 4689.1588797992. The cubic root of 21988211 is about 280.1538737567.

The spelling of 21988211 in words is "twenty-one million, nine hundred eighty-eight thousand, two hundred eleven".