21682499 has 2 divisors, whose sum is σ = 21682500. Its totient is φ = 21682498.

The previous prime is 21682487. The next prime is 21682501. The reversal of 21682499 is 99428612.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21682499 - 2²⁴ = 4905283 is a prime.

Together with 21682501, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21682099) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10841249 + 10841250.

It is an arithmetic number, because the mean of its divisors is an integer number (10841250).

Almost surely, 2^21682499 is an apocalyptic number.

21682499 is a deficient number, since it is larger than the sum of its proper divisors (1).

21682499 is an equidigital number, since it uses as much as digits as its factorization.

21682499 is an evil number, because the sum of its binary digits is even.

The product of its digits is 62208, while the sum is 41.

The square root of 21682499 is about 4656.4470360995. The cubic root of 21682499 is about 278.8494410842.

The spelling of 21682499 in words is "twenty-one million, six hundred eighty-two thousand, four hundred ninety-nine".