78402217 has 4 divisors (see below), whose sum is σ = 79135056. Its totient is φ = 77669380.

The previous prime is 78402199. The next prime is 78402229. The reversal of 78402217 is 71220487.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 78402217 - 2⁷ = 78402089 is a prime.

It is a super-2 number, since 2×78402217² = 12293815261030178, which contains 22 as substring.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78403217) 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, 366259 + ... + 366472.

It is an arithmetic number, because the mean of its divisors is an integer number (19783764).

Almost surely, 2^78402217 is an apocalyptic number.

It is an amenable number.

78402217 is a deficient number, since it is larger than the sum of its proper divisors (732839).

78402217 is a wasteful number, since it uses less digits than its factorization.

78402217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 732838.

The product of its (nonzero) digits is 6272, while the sum is 31.

The square root of 78402217 is about 8854.5026399002. The cubic root of 78402217 is about 427.9990264775. Note that the first 3 decimals are identical.

The spelling of 78402217 in words is "seventy-eight million, four hundred two thousand, two hundred seventeen".