78878134623721 has 4 divisors (see below), whose sum is σ = 78879582010000. Its totient is φ = 78876687237444.

The previous prime is 78878134623719. The next prime is 78878134623737. The reversal of 78878134623721 is 12732643187887.

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.

It is a cyclic number.

It is not a de Polignac number, because 78878134623721 - 2¹ = 78878134623719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78878134623751) 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, 723611391 + ... + 723720388.

It is an arithmetic number, because the mean of its divisors is an integer number (19719895502500).

Almost surely, 2^{78878134623721} is an apocalyptic number.

It is an amenable number.

78878134623721 is a deficient number, since it is larger than the sum of its proper divisors (1447386279).

78878134623721 is a wasteful number, since it uses less digits than its factorization.

78878134623721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1447386278.

The product of its digits is 151732224, while the sum is 67.

The spelling of 78878134623721 in words is "seventy-eight trillion, eight hundred seventy-eight billion, one hundred thirty-four million, six hundred twenty-three thousand, seven hundred twenty-one".