20864819 has 4 divisors (see below), whose sum is σ = 21218520. Its totient is φ = 20511120.

The previous prime is 20864807. The next prime is 20864821. The reversal of 20864819 is 91846802.

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 20864819 - 2⁴ = 20864803 is a prime.

It is a super-2 number, since 2×20864819² = 870681343805522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20864849) 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, 176762 + ... + 176879.

It is an arithmetic number, because the mean of its divisors is an integer number (5304630).

Almost surely, 2^20864819 is an apocalyptic number.

20864819 is a deficient number, since it is larger than the sum of its proper divisors (353701).

20864819 is an equidigital number, since it uses as much as digits as its factorization.

20864819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 353700.

The product of its (nonzero) digits is 27648, while the sum is 38.

The square root of 20864819 is about 4567.8024256747. The cubic root of 20864819 is about 275.2991521425.

The spelling of 20864819 in words is "twenty million, eight hundred sixty-four thousand, eight hundred nineteen".