21187547055837 has 16 divisors (see below), whose sum is σ = 31463516714560. Its totient is φ = 14091480219600.

The previous prime is 21187547055791. The next prime is 21187547055847. The reversal of 21187547055837 is 73855074578112.

21187547055837 is a `hidden beast` number, since 2 + 1 + 1 + 8 + 7 + 5 + 4 + 70 + 558 + 3 + 7 = 666.

It is not a de Polignac number, because 21187547055837 - 2¹⁴ = 21187547039453 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21187547055847) 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 15 ways as a sum of consecutive naturals, for example, 931964839 + ... + 931987572.

It is an arithmetic number, because the mean of its divisors is an integer number (1966469794660).

Almost surely, 2^{21187547055837} is an apocalyptic number.

21187547055837 is a gapful number since it is divisible by the number (27) formed by its first and last digit.

It is an amenable number.

21187547055837 is a deficient number, since it is larger than the sum of its proper divisors (10275969658723).

21187547055837 is a wasteful number, since it uses less digits than its factorization.

21187547055837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1863952841 (or 1863952835 counting only the distinct ones).

The product of its (nonzero) digits is 65856000, while the sum is 63.

The spelling of 21187547055837 in words is "twenty-one trillion, one hundred eighty-seven billion, five hundred forty-seven million, fifty-five thousand, eight hundred thirty-seven".