20644919 has 4 divisors (see below), whose sum is σ = 21859344. Its totient is φ = 19430496.

The previous prime is 20644909. The next prime is 20644973. The reversal of 20644919 is 91944602.

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 20644919 - 2⁴ = 20644903 is a prime.

It is a super-2 number, since 2×20644919² = 852425361033122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20644909) 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, 607187 + ... + 607220.

It is an arithmetic number, because the mean of its divisors is an integer number (5464836).

Almost surely, 2^20644919 is an apocalyptic number.

20644919 is a deficient number, since it is larger than the sum of its proper divisors (1214425).

20644919 is a wasteful number, since it uses less digits than its factorization.

20644919 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1214424.

The product of its (nonzero) digits is 15552, while the sum is 35.

The square root of 20644919 is about 4543.6680116399. The cubic root of 20644919 is about 274.3285835488.

The spelling of 20644919 in words is "twenty million, six hundred forty-four thousand, nine hundred nineteen".