20431271647 has 4 divisors (see below), whose sum is σ = 20983468216. Its totient is φ = 19879075080.

The previous prime is 20431271633. The next prime is 20431271671. The reversal of 20431271647 is 74617213402.

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 20431271647 - 2¹⁵ = 20431238879 is a prime.

It is a super-2 number, since 2×20431271647² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 552196531 = 20431271647 / (2 + 0 + 4 + 3 + 1 + 2 + 7 + 1 + 6 + 4 + 7).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20431271447) 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, 276098229 + ... + 276098302.

It is an arithmetic number, because the mean of its divisors is an integer number (5245867054).

Almost surely, 2^20431271647 is an apocalyptic number.

20431271647 is a deficient number, since it is larger than the sum of its proper divisors (552196569).

20431271647 is an equidigital number, since it uses as much as digits as its factorization.

20431271647 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 552196568.

The product of its (nonzero) digits is 56448, while the sum is 37.

The spelling of 20431271647 in words is "twenty billion, four hundred thirty-one million, two hundred seventy-one thousand, six hundred forty-seven".