21988319 has 2 divisors, whose sum is σ = 21988320. Its totient is φ = 21988318.

The previous prime is 21988313. The next prime is 21988367. The reversal of 21988319 is 91388912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21988319 - 2⁴ = 21988303 is a prime.

It is a super-2 number, since 2×21988319² = 966972344891522, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21988313) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10994159 + 10994160.

It is an arithmetic number, because the mean of its divisors is an integer number (10994160).

Almost surely, 2^21988319 is an apocalyptic number.

21988319 is a deficient number, since it is larger than the sum of its proper divisors (1).

21988319 is an equidigital number, since it uses as much as digits as its factorization.

21988319 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 41.

The square root of 21988319 is about 4689.1703957097. The cubic root of 21988319 is about 280.1543324353.

The spelling of 21988319 in words is "twenty-one million, nine hundred eighty-eight thousand, three hundred nineteen".