78223031163521 has 4 divisors (see below), whose sum is σ = 78223093391700. Its totient is φ = 78222968935344.

The previous prime is 78223031163517. The next prime is 78223031163587. The reversal of 78223031163521 is 12536113032287.

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 11662088400400 + 66560942763121 = 3414980^2 + 8158489^2 .

It is a cyclic number.

It is not a de Polignac number, because 78223031163521 - 2² = 78223031163517 is a prime.

It is a super-2 number, since 2×78223031163521² (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 (78223031163821) 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, 29188826 + ... + 31755843.

It is an arithmetic number, because the mean of its divisors is an integer number (19555773347925).

Almost surely, 2^{78223031163521} is an apocalyptic number.

It is an amenable number.

78223031163521 is a deficient number, since it is larger than the sum of its proper divisors (62228179).

78223031163521 is a wasteful number, since it uses less digits than its factorization.

78223031163521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62228178.

The product of its (nonzero) digits is 362880, while the sum is 44.

The spelling of 78223031163521 in words is "seventy-eight trillion, two hundred twenty-three billion, thirty-one million, one hundred sixty-three thousand, five hundred twenty-one".