20666219 has 4 divisors (see below), whose sum is σ = 23618544. Its totient is φ = 17713896.

The previous prime is 20666209. The next prime is 20666221. The reversal of 20666219 is 91266602.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20666219 - 2⁸ = 20665963 is a prime.

It is a super-2 number, since 2×20666219² = 854185215511922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20666209) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1476152 + ... + 1476165.

It is an arithmetic number, because the mean of its divisors is an integer number (5904636).

Almost surely, 2^20666219 is an apocalyptic number.

20666219 is a deficient number, since it is larger than the sum of its proper divisors (2952325).

20666219 is an equidigital number, since it uses as much as digits as its factorization.

20666219 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2952324.

The product of its (nonzero) digits is 7776, while the sum is 32.

The square root of 20666219 is about 4546.0113286264. The cubic root of 20666219 is about 274.4228955430.

The spelling of 20666219 in words is "twenty million, six hundred sixty-six thousand, two hundred nineteen".