21764219 has 2 divisors, whose sum is σ = 21764220. Its totient is φ = 21764218.

The previous prime is 21764191. The next prime is 21764221. The reversal of 21764219 is 91246712.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21764219 is a prime.

It is a super-2 number, since 2×21764219² = 947362457359922, which contains 22 as substring.

Together with 21764221, 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 (21764299) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10882109 + 10882110.

It is an arithmetic number, because the mean of its divisors is an integer number (10882110).

Almost surely, 2^21764219 is an apocalyptic number.

21764219 is a deficient number, since it is larger than the sum of its proper divisors (1).

21764219 is an equidigital number, since it uses as much as digits as its factorization.

21764219 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 32.

The square root of 21764219 is about 4665.2137142901. The cubic root of 21764219 is about 279.1993239982.

The spelling of 21764219 in words is "twenty-one million, seven hundred sixty-four thousand, two hundred nineteen".