991770400201212 has 18 divisors (see below), whose sum is σ = 2506975178286488. Its totient is φ = 330590133400392.

The previous prime is 991770400201129. The next prime is 991770400201213. The reversal of 991770400201212 is 212102004077199.

It is a happy number.

991770400201212 is a `hidden beast` number, since 9 + 9 + 1 + 7 + 7 + 0 + 400 + 20 + 1 + 212 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a super-2 number, since 2×991770400201212² (a number of 31 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991770400201213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 13774588891648 + ... + 13774588891719.

Almost surely, 2^{991770400201212} is an apocalyptic number.

It is an amenable number.

991770400201212 is an abundant number, since it is smaller than the sum of its proper divisors (1515204778085276).

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

991770400201212 is a wasteful number, since it uses less digits than its factorization.

991770400201212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27549177783377 (or 27549177783372 counting only the distinct ones).

The product of its (nonzero) digits is 127008, while the sum is 45.

The spelling of 991770400201212 in words is "nine hundred ninety-one trillion, seven hundred seventy billion, four hundred million, two hundred one thousand, two hundred twelve".