78221668 has 24 divisors (see below), whose sum is σ = 156691584. Its totient is φ = 33470400.

The previous prime is 78221621. The next prime is 78221681. The reversal of 78221668 is 86612287.

It is a super-2 number, since 2×78221668² = 12237258689404448, which contains 22 as substring.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 78221668.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19473 + ... + 23143.

It is an arithmetic number, because the mean of its divisors is an integer number (6528816).

Almost surely, 2^78221668 is an apocalyptic number.

It is an amenable number.

78221668 is an abundant number, since it is smaller than the sum of its proper divisors (78469916).

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

78221668 is a wasteful number, since it uses less digits than its factorization.

78221668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4443 (or 4441 counting only the distinct ones).

The product of its digits is 64512, while the sum is 40.

The square root of 78221668 is about 8844.3014421717. The cubic root of 78221668 is about 427.6702339477.

The spelling of 78221668 in words is "seventy-eight million, two hundred twenty-one thousand, six hundred sixty-eight".