20804381 has 4 divisors (see below), whose sum is σ = 22404732. Its totient is φ = 19204032.

The previous prime is 20804369. The next prime is 20804387. The reversal of 20804381 is 18340802.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18340802 = 2 ⋅9170401.

It can be written as a sum of positive squares in 2 ways, for example, as 12013156 + 8791225 = 3466^2 + 2965^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20804381 is a prime.

It is a super-2 number, since 2×20804381² = 865644537586322, 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 20804381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20804387) 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, 800156 + ... + 800181.

It is an arithmetic number, because the mean of its divisors is an integer number (5601183).

Almost surely, 2^20804381 is an apocalyptic number.

It is an amenable number.

20804381 is a deficient number, since it is larger than the sum of its proper divisors (1600351).

20804381 is a wasteful number, since it uses less digits than its factorization.

20804381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1600350.

The product of its (nonzero) digits is 1536, while the sum is 26.

The square root of 20804381 is about 4561.1819740063. The cubic root of 20804381 is about 275.0330803181.

The spelling of 20804381 in words is "twenty million, eight hundred four thousand, three hundred eighty-one".