78201891 has 24 divisors (see below), whose sum is σ = 119845440. Its totient is φ = 48999600.

The previous prime is 78201889. The next prime is 78201919. The reversal of 78201891 is 19810287.

It is not a de Polignac number, because 78201891 - 2¹ = 78201889 is a prime.

It is a super-3 number, since 3×78201891³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (78201841) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 20656 + ... + 24146.

It is an arithmetic number, because the mean of its divisors is an integer number (4993560).

Almost surely, 2^78201891 is an apocalyptic number.

78201891 is a deficient number, since it is larger than the sum of its proper divisors (41643549).

78201891 is a wasteful number, since it uses less digits than its factorization.

78201891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3647 (or 3644 counting only the distinct ones).

The product of its (nonzero) digits is 8064, while the sum is 36.

The square root of 78201891 is about 8843.1833069320. The cubic root of 78201891 is about 427.6341878949.

The spelling of 78201891 in words is "seventy-eight million, two hundred one thousand, eight hundred ninety-one".