20431571 has 4 divisors (see below), whose sum is σ = 20929944. Its totient is φ = 19933200.

The previous prime is 20431549. The next prime is 20431577. The reversal of 20431571 is 17513402.

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 20431571 - 2¹⁸ = 20169427 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20431577) 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, 249125 + ... + 249206.

It is an arithmetic number, because the mean of its divisors is an integer number (5232486).

Almost surely, 2^20431571 is an apocalyptic number.

20431571 is a deficient number, since it is larger than the sum of its proper divisors (498373).

20431571 is an equidigital number, since it uses as much as digits as its factorization.

20431571 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 498372.

The product of its (nonzero) digits is 840, while the sum is 23.

The square root of 20431571 is about 4520.1295335422. The cubic root of 20431571 is about 273.3803238994.

Adding to 20431571 its reverse (17513402), we get a palindrome (37944973).

The spelling of 20431571 in words is "twenty million, four hundred thirty-one thousand, five hundred seventy-one".