1971789887 has 4 divisors (see below), whose sum is σ = 1974028896. Its totient is φ = 1969550880.

The previous prime is 1971789881. The next prime is 1971789889. The reversal of 1971789887 is 7889871791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 7889871791 = 103 ⋅76600697.

It is a cyclic number.

It is not a de Polignac number, because 1971789887 - 2¹⁶ = 1971724351 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 (1971789881) 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, 1118183 + ... + 1119944.

It is an arithmetic number, because the mean of its divisors is an integer number (493507224).

Almost surely, 2^1971789887 is an apocalyptic number.

1971789887 is a deficient number, since it is larger than the sum of its proper divisors (2239009).

1971789887 is an equidigital number, since it uses as much as digits as its factorization.

1971789887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2239008.

The product of its digits is 14224896, while the sum is 65.

The square root of 1971789887 is about 44404.8408059302. The cubic root of 1971789887 is about 1253.9692254190.

The spelling of 1971789887 in words is "one billion, nine hundred seventy-one million, seven hundred eighty-nine thousand, eight hundred eighty-seven".