6601963991 has 24 divisors (see below), whose sum is σ = 8559589680. Its totient is φ = 5045628672.

The previous prime is 6601963987. The next prime is 6601964009. The reversal of 6601963991 is 1993691066.

It is a happy number.

It is not a de Polignac number, because 6601963991 - 2² = 6601963987 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6601963961) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 192740 + ... + 224393.

It is an arithmetic number, because the mean of its divisors is an integer number (356649570).

Almost surely, 2^6601963991 is an apocalyptic number.

6601963991 is a deficient number, since it is larger than the sum of its proper divisors (1957625689).

6601963991 is a wasteful number, since it uses less digits than its factorization.

6601963991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417183 (or 417176 counting only the distinct ones).

The product of its (nonzero) digits is 472392, while the sum is 50.

The square root of 6601963991 is about 81252.4706762816. The cubic root of 6601963991 is about 1875.9634980274.

The spelling of 6601963991 in words is "six billion, six hundred one million, nine hundred sixty-three thousand, nine hundred ninety-one".