21673999 has 2 divisors, whose sum is σ = 21674000. Its totient is φ = 21673998.

The previous prime is 21673973. The next prime is 21674011. The reversal of 21673999 is 99937612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21673999 - 2¹⁵ = 21641231 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21673969) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10836999 + 10837000.

It is an arithmetic number, because the mean of its divisors is an integer number (10837000).

Almost surely, 2^21673999 is an apocalyptic number.

21673999 is a deficient number, since it is larger than the sum of its proper divisors (1).

21673999 is an equidigital number, since it uses as much as digits as its factorization.

21673999 is an evil number, because the sum of its binary digits is even.

The product of its digits is 183708, while the sum is 46.

The square root of 21673999 is about 4655.5342335762. The cubic root of 21673999 is about 278.8129980210.

The spelling of 21673999 in words is "twenty-one million, six hundred seventy-three thousand, nine hundred ninety-nine".