78221536 has 24 divisors (see below), whose sum is σ = 157278240. Its totient is φ = 38277888.

The previous prime is 78221519. The next prime is 78221543. The reversal of 78221536 is 63512287.

It is a happy number.

It is a super-2 number, since 2×78221536² = 12237217388398592, which 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 3 ways as a sum of consecutive naturals, for example, 24501 + ... + 27508.

It is an arithmetic number, because the mean of its divisors is an integer number (6553260).

Almost surely, 2^78221536 is an apocalyptic number.

It is an amenable number.

78221536 is an abundant number, since it is smaller than the sum of its proper divisors (79056704).

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

78221536 is a wasteful number, since it uses less digits than its factorization.

78221536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52066 (or 52058 counting only the distinct ones).

The product of its digits is 20160, while the sum is 34.

The square root of 78221536 is about 8844.2939797363. The cubic root of 78221536 is about 427.6699933814.

The spelling of 78221536 in words is "seventy-eight million, two hundred twenty-one thousand, five hundred thirty-six".