21988263 has 16 divisors (see below), whose sum is σ = 33667200. Its totient is φ = 12624480.

The previous prime is 21988247. The next prime is 21988279. The reversal of 21988263 is 36288912.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21988247) and next prime (21988279).

It is not a de Polignac number, because 21988263 - 2⁴ = 21988247 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21988763) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16908 + ... + 18161.

It is an arithmetic number, because the mean of its divisors is an integer number (2104200).

Almost surely, 2^21988263 is an apocalyptic number.

21988263 is a deficient number, since it is larger than the sum of its proper divisors (11678937).

21988263 is a wasteful number, since it uses less digits than its factorization.

21988263 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35102.

The product of its digits is 41472, while the sum is 39.

The square root of 21988263 is about 4689.1644245004. The cubic root of 21988263 is about 280.1540946021.

The spelling of 21988263 in words is "twenty-one million, nine hundred eighty-eight thousand, two hundred sixty-three".