78216571420321 has 4 divisors (see below), whose sum is σ = 78541121509444. Its totient is φ = 77892021331200.

The previous prime is 78216571420307. The next prime is 78216571420447. The reversal of 78216571420321 is 12302417561287.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 68888672006400 + 9327899413921 = 8299920^2 + 3054161^2 .

It is a cyclic number.

It is not a de Polignac number, because 78216571420321 - 2⁹ = 78216571419809 is a prime.

It is a super-2 number, since 2×78216571420321² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78216571420921) 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, 162275044200 + ... + 162275044681.

It is an arithmetic number, because the mean of its divisors is an integer number (19635280377361).

Almost surely, 2^{78216571420321} is an apocalyptic number.

It is an amenable number.

78216571420321 is a deficient number, since it is larger than the sum of its proper divisors (324550089123).

78216571420321 is a wasteful number, since it uses less digits than its factorization.

78216571420321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 324550089122.

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

The spelling of 78216571420321 in words is "seventy-eight trillion, two hundred sixteen billion, five hundred seventy-one million, four hundred twenty thousand, three hundred twenty-one".