5991661994 has 4 divisors (see below), whose sum is σ = 8987492994. Its totient is φ = 2995830996.

The previous prime is 5991661993. The next prime is 5991661999. The reversal of 5991661994 is 4991661995.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 4991661995 = 5 ⋅998332399.

It can be written as a sum of positive squares in only one way, i.e., 5697985225 + 293676769 = 75485^2 + 17137^2 .

It is not an unprimeable number, because it can be changed into a prime (5991661993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1497915497 + ... + 1497915500.

Almost surely, 2^5991661994 is an apocalyptic number.

5991661994 is a deficient number, since it is larger than the sum of its proper divisors (2995831000).

5991661994 is a wasteful number, since it uses less digits than its factorization.

5991661994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2995830999.

The product of its digits is 4723920, while the sum is 59.

The square root of 5991661994 is about 77405.8266153137. The cubic root of 5991661994 is about 1816.2784713772.

Subtracting from 5991661994 its reverse (4991661995), we obtain a palindrome (999999999).

The spelling of 5991661994 in words is "five billion, nine hundred ninety-one million, six hundred sixty-one thousand, nine hundred ninety-four".