21186187870 has 16 divisors (see below), whose sum is σ = 38781497520. Its totient is φ = 8330839744.

The previous prime is 21186187843. The next prime is 21186187871. The reversal of 21186187870 is 7878168112.

21186187870 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21186187871) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17953807 + ... + 17954986.

It is an arithmetic number, because the mean of its divisors is an integer number (2423843595).

Almost surely, 2^21186187870 is an apocalyptic number.

21186187870 is a deficient number, since it is larger than the sum of its proper divisors (17595309650).

21186187870 is a wasteful number, since it uses less digits than its factorization.

21186187870 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35908859.

The product of its (nonzero) digits is 301056, while the sum is 49.

The spelling of 21186187870 in words is "twenty-one billion, one hundred eighty-six million, one hundred eighty-seven thousand, eight hundred seventy".