7987138821 has 12 divisors (see below), whose sum is σ = 11537798272. Its totient is φ = 5324380776.

The previous prime is 7987138801. The next prime is 7987138843. The reversal of 7987138821 is 1288317897.

It is a happy number.

It is not a de Polignac number, because 7987138821 - 2¹³ = 7987130629 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 (7987138801) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 169740 + ... + 211626.

Almost surely, 2^7987138821 is an apocalyptic number.

It is an amenable number.

7987138821 is a deficient number, since it is larger than the sum of its proper divisors (3550659451).

7987138821 is a wasteful number, since it uses less digits than its factorization.

7987138821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63080 (or 63077 counting only the distinct ones).

The product of its digits is 1354752, while the sum is 54.

The square root of 7987138821 is about 89370.7940045292. The cubic root of 7987138821 is about 1998.9276602298.

The spelling of 7987138821 in words is "seven billion, nine hundred eighty-seven million, one hundred thirty-eight thousand, eight hundred twenty-one".