991263641586 has 16 divisors (see below), whose sum is σ = 1982572827168. Its totient is φ = 330413623200.

The previous prime is 991263641551. The next prime is 991263641591. The reversal of 991263641586 is 685146362199.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1611400 + ... + 2139891.

It is an arithmetic number, because the mean of its divisors is an integer number (123910801698).

Almost surely, 2^991263641586 is an apocalyptic number.

991263641586 is an abundant number, since it is smaller than the sum of its proper divisors (991309185582).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

991263641586 is a wasteful number, since it uses less digits than its factorization.

991263641586 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3795337.

The product of its digits is 16796160, while the sum is 60.

The spelling of 991263641586 in words is "nine hundred ninety-one billion, two hundred sixty-three million, six hundred forty-one thousand, five hundred eighty-six".