1971391867 has 4 divisors (see below), whose sum is σ = 1978358200. Its totient is φ = 1964425536.

The previous prime is 1971391843. The next prime is 1971391871. The reversal of 1971391867 is 7681931791.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1971391867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1971391817) 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, 3482742 + ... + 3483307.

It is an arithmetic number, because the mean of its divisors is an integer number (494589550).

Almost surely, 2^1971391867 is an apocalyptic number.

1971391867 is a deficient number, since it is larger than the sum of its proper divisors (6966333).

1971391867 is an equidigital number, since it uses as much as digits as its factorization.

1971391867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6966332.

The product of its digits is 571536, while the sum is 52.

The square root of 1971391867 is about 44400.3588611624. The cubic root of 1971391867 is about 1253.8848454993.

The spelling of 1971391867 in words is "one billion, nine hundred seventy-one million, three hundred ninety-one thousand, eight hundred sixty-seven".