38515916721 has 4 divisors (see below), whose sum is σ = 51354555632. Its totient is φ = 25677277812.

The previous prime is 38515916713. The next prime is 38515916729. The reversal of 38515916721 is 12761951583.

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: 12761951583 = 3 ⋅4253983861.

It is an interprime number because it is at equal distance from previous prime (38515916713) and next prime (38515916729).

It is not a de Polignac number, because 38515916721 - 2³ = 38515916713 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (38515916729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6419319451 + ... + 6419319456.

It is an arithmetic number, because the mean of its divisors is an integer number (12838638908).

Almost surely, 2^38515916721 is an apocalyptic number.

It is an amenable number.

38515916721 is a deficient number, since it is larger than the sum of its proper divisors (12838638911).

38515916721 is a wasteful number, since it uses less digits than its factorization.

38515916721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12838638910.

The product of its digits is 453600, while the sum is 48.

The spelling of 38515916721 in words is "thirty-eight billion, five hundred fifteen million, nine hundred sixteen thousand, seven hundred twenty-one".