20380729 has 4 divisors (see below), whose sum is σ = 20405476. Its totient is φ = 20355984.

The previous prime is 20380721. The next prime is 20380769. The reversal of 20380729 is 92708302.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9753129 + 10627600 = 3123^2 + 3260^2 .

It is a cyclic number.

It is not a de Polignac number, because 20380729 - 2³ = 20380721 is a prime.

It is a super-2 number, since 2×20380729² = 830748229142882, 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 20380729.

It is not an unprimeable number, because it can be changed into a prime (20380721) 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, 11094 + ... + 12799.

It is an arithmetic number, because the mean of its divisors is an integer number (5101369).

Almost surely, 2^20380729 is an apocalyptic number.

It is an amenable number.

20380729 is a deficient number, since it is larger than the sum of its proper divisors (24747).

20380729 is an equidigital number, since it uses as much as digits as its factorization.

20380729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24746.

The product of its (nonzero) digits is 6048, while the sum is 31.

The square root of 20380729 is about 4514.5020766415. The cubic root of 20380729 is about 273.1533753315.

The spelling of 20380729 in words is "twenty million, three hundred eighty thousand, seven hundred twenty-nine".