19890771391 has 4 divisors (see below), whose sum is σ = 19935072000. Its totient is φ = 19846470784.

The previous prime is 19890771389. The next prime is 19890771419. The reversal of 19890771391 is 19317709891.

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 19890771391 - 2¹ = 19890771389 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 (19890771371) 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, 22149631 + ... + 22150528.

It is an arithmetic number, because the mean of its divisors is an integer number (4983768000).

Almost surely, 2^19890771391 is an apocalyptic number.

19890771391 is a deficient number, since it is larger than the sum of its proper divisors (44300609).

19890771391 is an equidigital number, since it uses as much as digits as its factorization.

19890771391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44300608.

The product of its (nonzero) digits is 857304, while the sum is 55.

The spelling of 19890771391 in words is "nineteen billion, eight hundred ninety million, seven hundred seventy-one thousand, three hundred ninety-one".