18743387521 has 4 divisors (see below), whose sum is σ = 18744871600. Its totient is φ = 18741903444.

The previous prime is 18743387437. The next prime is 18743387563. The reversal of 18743387521 is 12578334781.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 12578334781 = 96487 ⋅130363.

It is a cyclic number.

It is not a de Polignac number, because 18743387521 - 2³¹ = 16595903873 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18743387321) 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, 722931 + ... + 748408.

It is an arithmetic number, because the mean of its divisors is an integer number (4686217900).

Almost surely, 2^18743387521 is an apocalyptic number.

It is an amenable number.

18743387521 is a deficient number, since it is larger than the sum of its proper divisors (1484079).

18743387521 is a wasteful number, since it uses less digits than its factorization.

18743387521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1484078.

The product of its digits is 1128960, while the sum is 49.

The spelling of 18743387521 in words is "eighteen billion, seven hundred forty-three million, three hundred eighty-seven thousand, five hundred twenty-one".