21387100557 has 8 divisors (see below), whose sum is σ = 28527797376. Its totient is φ = 14252235392.

The previous prime is 21387100543. The next prime is 21387100633. The reversal of 21387100557 is 75500178312.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21387100557 - 2⁷ = 21387100429 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21387100507) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1449348 + ... + 1464029.

It is an arithmetic number, because the mean of its divisors is an integer number (3565974672).

Almost surely, 2^21387100557 is an apocalyptic number.

It is an amenable number.

21387100557 is a deficient number, since it is larger than the sum of its proper divisors (7140696819).

21387100557 is a wasteful number, since it uses less digits than its factorization.

21387100557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2915827.

The product of its (nonzero) digits is 58800, while the sum is 39.

Adding to 21387100557 its reverse (75500178312), we get a palindrome (96887278869).

The spelling of 21387100557 in words is "twenty-one billion, three hundred eighty-seven million, one hundred thousand, five hundred fifty-seven".