20403881 has 4 divisors (see below), whose sum is σ = 20507652. Its totient is φ = 20300112.

The previous prime is 20403871. The next prime is 20403899. The reversal of 20403881 is 18830402.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18830402 = 2 ⋅9415201.

It can be written as a sum of positive squares in 2 ways, for example, as 9241600 + 11162281 = 3040^2 + 3341^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20403881 is a prime.

It is a super-2 number, since 2×20403881² = 832636719724322, 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 20403881.

It is not an unprimeable number, because it can be changed into a prime (20403811) 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, 51590 + ... + 51983.

It is an arithmetic number, because the mean of its divisors is an integer number (5126913).

Almost surely, 2^20403881 is an apocalyptic number.

It is an amenable number.

20403881 is a deficient number, since it is larger than the sum of its proper divisors (103771).

20403881 is a wasteful number, since it uses less digits than its factorization.

20403881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103770.

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

The square root of 20403881 is about 4517.0655297438. The cubic root of 20403881 is about 273.2567679989.

The spelling of 20403881 in words is "twenty million, four hundred three thousand, eight hundred eighty-one".