20939643 has 12 divisors (see below), whose sum is σ = 30984408. Its totient is φ = 13619040.

The previous prime is 20939641. The next prime is 20939647. The reversal of 20939643 is 34693902.

It is a happy number.

20939643 is a `hidden beast` number, since 2 + 0 + 9 + 3 + 9 + 643 = 666.

It is not a de Polignac number, because 20939643 - 2¹ = 20939641 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20939598 and 20939607.

It is not an unprimeable number, because it can be changed into a prime (20939641) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28005 + ... + 28742.

It is an arithmetic number, because the mean of its divisors is an integer number (2582034).

Almost surely, 2^20939643 is an apocalyptic number.

20939643 is a deficient number, since it is larger than the sum of its proper divisors (10044765).

20939643 is a wasteful number, since it uses less digits than its factorization.

20939643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56794 (or 56791 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 36.

The square root of 20939643 is about 4575.9854676343. The cubic root of 20939643 is about 275.6278459299.

The spelling of 20939643 in words is "twenty million, nine hundred thirty-nine thousand, six hundred forty-three".