20731369 has 4 divisors (see below), whose sum is σ = 20740996. Its totient is φ = 20721744.

The previous prime is 20731351. The next prime is 20731391. The reversal of 20731369 is 96313702.

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 19465744 + 1265625 = 4412^2 + 1125^2 .

It is a cyclic number.

It is not a de Polignac number, because 20731369 - 2⁷ = 20731241 is a prime.

It is a super-2 number, since 2×20731369² = 859579321228322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20731369.

It is not an unprimeable number, because it can be changed into a prime (20731309) 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, 67 + ... + 6439.

It is an arithmetic number, because the mean of its divisors is an integer number (5185249).

Almost surely, 2^20731369 is an apocalyptic number.

It is an amenable number.

20731369 is a deficient number, since it is larger than the sum of its proper divisors (9627).

20731369 is an equidigital number, since it uses as much as digits as its factorization.

20731369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9626.

The product of its (nonzero) digits is 6804, while the sum is 31.

The square root of 20731369 is about 4553.1713123932. The cubic root of 20731369 is about 274.7109646389.

The spelling of 20731369 in words is "twenty million, seven hundred thirty-one thousand, three hundred sixty-nine".