21991461876 has 96 divisors (see below), whose sum is σ = 59563929600. Its totient is φ = 7008461280.

The previous prime is 21991461841. The next prime is 21991461887. The reversal of 21991461876 is 67816419912.

21991461876 is a `hidden beast` number, since 2 + 1 + 9 + 9 + 14 + 618 + 7 + 6 = 666.

It is a super-2 number, since 2×21991461876² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 238315 + ... + 317453.

It is an arithmetic number, because the mean of its divisors is an integer number (620457600).

Almost surely, 2^21991461876 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21991461876, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29781964800).

21991461876 is an abundant number, since it is smaller than the sum of its proper divisors (37572467724).

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

21991461876 is a wasteful number, since it uses less digits than its factorization.

21991461876 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79266 (or 79258 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 54.

It can be divided in two parts, 2199146 and 1876, that added together give a palindrome (2201022).

The spelling of 21991461876 in words is "twenty-one billion, nine hundred ninety-one million, four hundred sixty-one thousand, eight hundred seventy-six".