21744406387 has 4 divisors (see below), whose sum is σ = 23721170616. Its totient is φ = 19767642160.

The previous prime is 21744406339. The next prime is 21744406391. The reversal of 21744406387 is 78360444712.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21744406387 - 2¹⁹ = 21743882099 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21744406487) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 988382098 + ... + 988382119.

It is an arithmetic number, because the mean of its divisors is an integer number (5930292654).

Almost surely, 2^21744406387 is an apocalyptic number.

21744406387 is a deficient number, since it is larger than the sum of its proper divisors (1976764229).

21744406387 is a wasteful number, since it uses less digits than its factorization.

21744406387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1976764228.

The product of its (nonzero) digits is 903168, while the sum is 46.

The spelling of 21744406387 in words is "twenty-one billion, seven hundred forty-four million, four hundred six thousand, three hundred eighty-seven".