1967998391 has 4 divisors (see below), whose sum is σ = 1973137152. Its totient is φ = 1962859632.

The previous prime is 1967998367. The next prime is 1967998399. The reversal of 1967998391 is 1938997691.

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 1967998391 - 2¹⁴ = 1967982007 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1967998399) 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, 2568806 + ... + 2569571.

It is an arithmetic number, because the mean of its divisors is an integer number (493284288).

Almost surely, 2^1967998391 is an apocalyptic number.

1967998391 is a deficient number, since it is larger than the sum of its proper divisors (5138761).

1967998391 is an equidigital number, since it uses as much as digits as its factorization.

1967998391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5138760.

The product of its digits is 6613488, while the sum is 62.

The square root of 1967998391 is about 44362.1278908034. The cubic root of 1967998391 is about 1253.1649696901.

The spelling of 1967998391 in words is "one billion, nine hundred sixty-seven million, nine hundred ninety-eight thousand, three hundred ninety-one".