18735721387 has 2 divisors, whose sum is σ = 18735721388. Its totient is φ = 18735721386.

The previous prime is 18735721373. The next prime is 18735721391. The reversal of 18735721387 is 78312753781.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 18735721387 - 2¹⁵ = 18735688619 is a prime.

It is not a weakly prime, because it can be changed into another prime (18735721337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9367860693 + 9367860694.

It is an arithmetic number, because the mean of its divisors is an integer number (9367860694).

Almost surely, 2^18735721387 is an apocalyptic number.

18735721387 is a deficient number, since it is larger than the sum of its proper divisors (1).

18735721387 is an equidigital number, since it uses as much as digits as its factorization.

18735721387 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1975680, while the sum is 52.

The spelling of 18735721387 in words is "eighteen billion, seven hundred thirty-five million, seven hundred twenty-one thousand, three hundred eighty-seven".