78136221 has 8 divisors (see below), whose sum is σ = 108711360. Its totient is φ = 49825952.

The previous prime is 78136217. The next prime is 78136229. The reversal of 78136221 is 12263187.

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

It is a cyclic number.

It is not a de Polignac number, because 78136221 - 2² = 78136217 is a prime.

It is a super-2 number, since 2×78136221² = 12210538064321682, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78136229) 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, 566136 + ... + 566273.

It is an arithmetic number, because the mean of its divisors is an integer number (13588920).

Almost surely, 2^78136221 is an apocalyptic number.

It is an amenable number.

78136221 is a deficient number, since it is larger than the sum of its proper divisors (30575139).

78136221 is a wasteful number, since it uses less digits than its factorization.

78136221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1132435.

The product of its digits is 4032, while the sum is 30.

The square root of 78136221 is about 8839.4694976565. The cubic root of 78136221 is about 427.5144525055.

The spelling of 78136221 in words is "seventy-eight million, one hundred thirty-six thousand, two hundred twenty-one".