76391507821 has 4 divisors (see below), whose sum is σ = 77686279200. Its totient is φ = 75096736444.

The previous prime is 76391507813. The next prime is 76391507849. The reversal of 76391507821 is 12870519367.

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: 12870519367 = 29017 ⋅443551.

It is a cyclic number.

It is not a de Polignac number, because 76391507821 - 2³ = 76391507813 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 (76391507021) 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, 647385601 + ... + 647385718.

It is an arithmetic number, because the mean of its divisors is an integer number (19421569800).

Almost surely, 2^76391507821 is an apocalyptic number.

It is an amenable number.

76391507821 is a deficient number, since it is larger than the sum of its proper divisors (1294771379).

76391507821 is a wasteful number, since it uses less digits than its factorization.

76391507821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1294771378.

The product of its (nonzero) digits is 635040, while the sum is 49.

The spelling of 76391507821 in words is "seventy-six billion, three hundred ninety-one million, five hundred seven thousand, eight hundred twenty-one".