78221667 has 4 divisors (see below), whose sum is σ = 104295560. Its totient is φ = 52147776.

The previous prime is 78221621. The next prime is 78221681. The reversal of 78221667 is 76612287.

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

It is not a de Polignac number, because 78221667 - 2⁶ = 78221603 is a prime.

It is a super-2 number, since 2×78221667² = 12237258376517778, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78221467) 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, 13036942 + ... + 13036947.

It is an arithmetic number, because the mean of its divisors is an integer number (26073890).

Almost surely, 2^78221667 is an apocalyptic number.

78221667 is a deficient number, since it is larger than the sum of its proper divisors (26073893).

78221667 is a wasteful number, since it uses less digits than its factorization.

78221667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26073892.

The product of its digits is 56448, while the sum is 39.

The square root of 78221667 is about 8844.3013856381. The cubic root of 78221667 is about 427.6702321253.

The spelling of 78221667 in words is "seventy-eight million, two hundred twenty-one thousand, six hundred sixty-seven".