21907857219889 has 3 divisors (see below), whose sum is σ = 21907861900473. Its totient is φ = 21907852539306.

The previous prime is 21907857219863. The next prime is 21907857219901. The reversal of 21907857219889 is 98891275870912.

The square root of 21907857219889 is 4680583.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a de Polignac number, because none of the positive numbers 2^k-21907857219889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21907857259889) by changing a digit.

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 2 ways as a sum of consecutive naturals, for example, 2340292 + ... + 7020874.

It is an arithmetic number, because the mean of its divisors is an integer number (7302620633491).

Almost surely, 2^{21907857219889} is an apocalyptic number.

21907857219889 is the 4680583-rd square number.

21907857219889 is the 2340292-nd centered octagonal number.

It is an amenable number.

21907857219889 is a deficient number, since it is larger than the sum of its proper divisors (4680584).

21907857219889 is an frugal number, since it uses more digits than its factorization.

21907857219889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9361166 (or 4680583 counting only the distinct ones).

The product of its (nonzero) digits is 365783040, while the sum is 76.

The spelling of 21907857219889 in words is "twenty-one trillion, nine hundred seven billion, eight hundred fifty-seven million, two hundred nineteen thousand, eight hundred eighty-nine".