1989668477 has 4 divisors (see below), whose sum is σ = 1990939776. Its totient is φ = 1988397180.

The previous prime is 1989668449. The next prime is 1989668497. The reversal of 1989668477 is 7748669891.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 7748669891 = 79 ⋅98084429.

It is a cyclic number.

It is not a de Polignac number, because 1989668477 - 2¹⁰ = 1989667453 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 (1989668497) 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, 633299 + ... + 636432.

It is an arithmetic number, because the mean of its divisors is an integer number (497734944).

Almost surely, 2^1989668477 is an apocalyptic number.

It is an amenable number.

1989668477 is a deficient number, since it is larger than the sum of its proper divisors (1271299).

1989668477 is a wasteful number, since it uses less digits than its factorization.

1989668477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1271298.

The product of its digits is 36578304, while the sum is 65.

The square root of 1989668477 is about 44605.7000505541. The cubic root of 1989668477 is about 1257.7478195739.

The spelling of 1989668477 in words is "one billion, nine hundred eighty-nine million, six hundred sixty-eight thousand, four hundred seventy-seven".