20439881 has 16 divisors (see below), whose sum is σ = 26308608. Its totient is φ = 15411600.

The previous prime is 20439871. The next prime is 20439911. The reversal of 20439881 is 18893402.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20439881 - 2¹⁸ = 20177737 is a prime.

It is a super-2 number, since 2×20439881² = 835577470588322, which contains 22 as substring.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20439841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1895 + ... + 6668.

It is an arithmetic number, because the mean of its divisors is an integer number (1644288).

Almost surely, 2^20439881 is an apocalyptic number.

It is an amenable number.

20439881 is a deficient number, since it is larger than the sum of its proper divisors (5868727).

20439881 is a wasteful number, since it uses less digits than its factorization.

20439881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8612.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 20439881 is about 4521.0486615386. The cubic root of 20439881 is about 273.4173822761.

The spelling of 20439881 in words is "twenty million, four hundred thirty-nine thousand, eight hundred eighty-one".