78291215 has 4 divisors (see below), whose sum is σ = 93949464. Its totient is φ = 62632968.

The previous prime is 78291209. The next prime is 78291247. The reversal of 78291215 is 51219287.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 51219287 = 7 ⋅7317041.

It is a cyclic number.

It is not a de Polignac number, because 78291215 - 2²⁰ = 77242639 is a prime.

It is a super-2 number, since 2×78291215² = 12259028692352450, which contains 22 as substring.

It is a Duffinian number.

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, 7829117 + ... + 7829126.

It is an arithmetic number, because the mean of its divisors is an integer number (23487366).

Almost surely, 2^78291215 is an apocalyptic number.

78291215 is a deficient number, since it is larger than the sum of its proper divisors (15658249).

78291215 is a wasteful number, since it uses less digits than its factorization.

78291215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15658248.

The product of its digits is 10080, while the sum is 35.

The square root of 78291215 is about 8848.2323093373. The cubic root of 78291215 is about 427.7969438137.

The spelling of 78291215 in words is "seventy-eight million, two hundred ninety-one thousand, two hundred fifteen".