20219909 has 4 divisors (see below), whose sum is σ = 20229420. Its totient is φ = 20210400.

The previous prime is 20219893. The next prime is 20219911. The reversal of 20219909 is 90991202.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 11937025 + 8282884 = 3455^2 + 2878^2 .

It is a cyclic number.

It is not a de Polignac number, because 20219909 - 2⁴ = 20219893 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20219939) 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, 59 + ... + 6359.

It is an arithmetic number, because the mean of its divisors is an integer number (5057355).

Almost surely, 2^20219909 is an apocalyptic number.

It is an amenable number.

20219909 is a deficient number, since it is larger than the sum of its proper divisors (9511).

20219909 is an equidigital number, since it uses as much as digits as its factorization.

20219909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9510.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 20219909 is about 4496.6553125629. The cubic root of 20219909 is about 272.4330121791.

The spelling of 20219909 in words is "twenty million, two hundred nineteen thousand, nine hundred nine".