891187781197 has 16 divisors (see below), whose sum is σ = 1072132355200. Its totient is φ = 723653222400.

The previous prime is 891187781123. The next prime is 891187781207. The reversal of 891187781197 is 791187781198.

It is a cyclic number.

It is not a de Polignac number, because 891187781197 - 2²³ = 891179392589 is a prime.

It is a super-2 number, since 2×891187781197² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (891187785197) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8807629 + ... + 8908237.

It is an arithmetic number, because the mean of its divisors is an integer number (67008272200).

Almost surely, 2^891187781197 is an apocalyptic number.

It is an amenable number.

891187781197 is a deficient number, since it is larger than the sum of its proper divisors (180944574003).

891187781197 is a wasteful number, since it uses less digits than its factorization.

891187781197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167236.

The product of its digits is 14224896, while the sum is 67.

Subtracting from 891187781197 its reverse (791187781198), we obtain a palindrome (99999999999).

The spelling of 891187781197 in words is "eight hundred ninety-one billion, one hundred eighty-seven million, seven hundred eighty-one thousand, one hundred ninety-seven".