20993081 has 4 divisors (see below), whose sum is σ = 22098000. Its totient is φ = 19888164.

The previous prime is 20993059. The next prime is 20993083. The reversal of 20993081 is 18039902.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20993081 - 2⁶ = 20993017 is a prime.

It is a super-2 number, since 2×20993081² = 881418899745122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20993083) 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, 552431 + ... + 552468.

It is an arithmetic number, because the mean of its divisors is an integer number (5524500).

Almost surely, 2^20993081 is an apocalyptic number.

It is an amenable number.

20993081 is a deficient number, since it is larger than the sum of its proper divisors (1104919).

20993081 is a wasteful number, since it uses less digits than its factorization.

20993081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1104918.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 20993081 is about 4581.8207079719. The cubic root of 20993081 is about 275.8621143155.

The spelling of 20993081 in words is "twenty million, nine hundred ninety-three thousand, eighty-one".