78215091 has 8 divisors (see below), whose sum is σ = 105755904. Its totient is φ = 51408840.

The previous prime is 78215087. The next prime is 78215101. The reversal of 78215091 is 19051287.

Added to its reverse (19051287) it gives a triangular number (97266378 = T₁₃₉₄₇).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 78215091 - 2² = 78215087 is a prime.

It is a super-2 number, since 2×78215091² = 12235200920276562, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (78215041) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 183391 + ... + 183816.

It is an arithmetic number, because the mean of its divisors is an integer number (13219488).

Almost surely, 2^78215091 is an apocalyptic number.

78215091 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

78215091 is a deficient number, since it is larger than the sum of its proper divisors (27540813).

78215091 is a wasteful number, since it uses less digits than its factorization.

78215091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367281.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 78215091 is about 8843.9296130171. The cubic root of 78215091 is about 427.6582472181.

Adding to 78215091 its reverse (19051287), we get a triangular number (97266378 = T₁₃₉₄₇).

The spelling of 78215091 in words is "seventy-eight million, two hundred fifteen thousand, ninety-one".