78215887 has 4 divisors (see below), whose sum is σ = 79541640. Its totient is φ = 76890136.

The previous prime is 78215881. The next prime is 78215897. The reversal of 78215887 is 78851287.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 78215887 - 2¹⁹ = 77691599 is a prime.

It is a super-2 number, since 2×78215887² = 12235449958393538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78215881) 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, 662788 + ... + 662905.

It is an arithmetic number, because the mean of its divisors is an integer number (19885410).

Almost surely, 2^78215887 is an apocalyptic number.

78215887 is a deficient number, since it is larger than the sum of its proper divisors (1325753).

78215887 is a wasteful number, since it uses less digits than its factorization.

78215887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1325752.

The product of its digits is 250880, while the sum is 46.

The square root of 78215887 is about 8843.9746155221. The cubic root of 78215887 is about 427.6596979816.

The spelling of 78215887 in words is "seventy-eight million, two hundred fifteen thousand, eight hundred eighty-seven".