78172428 has 24 divisors (see below), whose sum is σ = 182552832. Its totient is φ = 26035984.

The previous prime is 78172417. The next prime is 78172439. The reversal of 78172428 is 82427187.

It is an interprime number because it is at equal distance from previous prime (78172417) and next prime (78172439).

It is a super-2 number, since 2×78172428² = 12221856998830368, which contains 22 as substring.

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, 20401 + ... + 23927.

It is an arithmetic number, because the mean of its divisors is an integer number (7606368).

Almost surely, 2^78172428 is an apocalyptic number.

It is an amenable number.

78172428 is an abundant number, since it is smaller than the sum of its proper divisors (104380404).

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

78172428 is a wasteful number, since it uses less digits than its factorization.

78172428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5381 (or 5379 counting only the distinct ones).

The product of its digits is 50176, while the sum is 39.

The square root of 78172428 is about 8841.5172906012. The cubic root of 78172428 is about 427.5804766246.

The spelling of 78172428 in words is "seventy-eight million, one hundred seventy-two thousand, four hundred twenty-eight".