20957143 has 4 divisors (see below), whose sum is σ = 20969928. Its totient is φ = 20944360.

The previous prime is 20957129. The next prime is 20957161. The reversal of 20957143 is 34175902.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20957143 - 2²¹ = 18859991 is a prime.

It is a Smith number, since the sum of its digits (31) 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 a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20957113) 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, 3496 + ... + 7357.

It is an arithmetic number, because the mean of its divisors is an integer number (5242482).

Almost surely, 2^20957143 is an apocalyptic number.

20957143 is a deficient number, since it is larger than the sum of its proper divisors (12785).

20957143 is a wasteful number, since it uses less digits than its factorization.

20957143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12784.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 20957143 is about 4577.8972247092. The cubic root of 20957143 is about 275.7046085281.

The spelling of 20957143 in words is "twenty million, nine hundred fifty-seven thousand, one hundred forty-three".