78213817820 has 24 divisors (see below), whose sum is σ = 165784059504. Its totient is φ = 30993138176.

The previous prime is 78213817769. The next prime is 78213817831. The reversal of 78213817820 is 2871831287.

It is a super-2 number, since 2×78213817820² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18272117 + ... + 18276396.

It is an arithmetic number, because the mean of its divisors is an integer number (6907669146).

Almost surely, 2^78213817820 is an apocalyptic number.

It is an amenable number.

78213817820 is an abundant number, since it is smaller than the sum of its proper divisors (87570241684).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

78213817820 is a wasteful number, since it uses less digits than its factorization.

78213817820 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36548629 (or 36548627 counting only the distinct ones).

The product of its (nonzero) digits is 301056, while the sum is 47.

The spelling of 78213817820 in words is "seventy-eight billion, two hundred thirteen million, eight hundred seventeen thousand, eight hundred twenty".