21165246387 has 24 divisors (see below), whose sum is σ = 31157478144. Its totient is φ = 13842517104.

The previous prime is 21165246371. The next prime is 21165246413. The reversal of 21165246387 is 78364256112.

21165246387 is a `hidden beast` number, since 2 + 1 + 1 + 6 + 5 + 2 + 4 + 638 + 7 = 666.

It is not a de Polignac number, because 21165246387 - 2⁴ = 21165246371 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21165246887) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 7503 + ... + 205880.

It is an arithmetic number, because the mean of its divisors is an integer number (1298228256).

Almost surely, 2^21165246387 is an apocalyptic number.

21165246387 is a deficient number, since it is larger than the sum of its proper divisors (9992231757).

21165246387 is a wasteful number, since it uses less digits than its factorization.

21165246387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 213599 (or 213596 counting only the distinct ones).

The product of its digits is 483840, while the sum is 45.

The spelling of 21165246387 in words is "twenty-one billion, one hundred sixty-five million, two hundred forty-six thousand, three hundred eighty-seven".