21387005197 has 4 divisors (see below), whose sum is σ = 21387383296. Its totient is φ = 21386627100.

The previous prime is 21387005177. The next prime is 21387005221. The reversal of 21387005197 is 79150078312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21387005197 - 2²⁷ = 21252787469 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 (21387005117) 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 3 ways as a sum of consecutive naturals, for example, 85179 + ... + 223672.

It is an arithmetic number, because the mean of its divisors is an integer number (5346845824).

Almost surely, 2^21387005197 is an apocalyptic number.

It is an amenable number.

21387005197 is a deficient number, since it is larger than the sum of its proper divisors (378099).

21387005197 is an equidigital number, since it uses as much as digits as its factorization.

21387005197 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 378098.

The product of its (nonzero) digits is 105840, while the sum is 43.

The spelling of 21387005197 in words is "twenty-one billion, three hundred eighty-seven million, five thousand, one hundred ninety-seven".