20138643 has 24 divisors (see below), whose sum is σ = 33372768. Its totient is φ = 11463552.

The previous prime is 20138641. The next prime is 20138669. The reversal of 20138643 is 34683102.

It is a happy number.

20138643 is a `hidden beast` number, since 2 + 0 + 13 + 8 + 643 = 666.

It is not a de Polignac number, because 20138643 - 2¹ = 20138641 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20138641) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23071 + ... + 23927.

It is an arithmetic number, because the mean of its divisors is an integer number (1390532).

Almost surely, 2^20138643 is an apocalyptic number.

20138643 is a deficient number, since it is larger than the sum of its proper divisors (13234125).

20138643 is a wasteful number, since it uses less digits than its factorization.

20138643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1243 (or 1240 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 27.

The square root of 20138643 is about 4487.6099429429. The cubic root of 20138643 is about 272.0675428789.

The spelling of 20138643 in words is "twenty million, one hundred thirty-eight thousand, six hundred forty-three".