78021889 has 15 divisors (see below), whose sum is σ = 87015315. Its totient is φ = 69957360.

The previous prime is 78021887. The next prime is 78021941. The reversal of 78021889 is 98812087.

The square root of 78021889 is 8833.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 44289025 + 33732864 = 6655^2 + 5808^2 .

It is not a de Polignac number, because 78021889 - 2¹ = 78021887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (78021887) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 1068757 + ... + 1068829.

It is an arithmetic number, because the mean of its divisors is an integer number (5801021).

Almost surely, 2^78021889 is an apocalyptic number.

78021889 is the 8833-rd square number.

78021889 is the 4417-th centered octagonal number.

It is an amenable number.

78021889 is a deficient number, since it is larger than the sum of its proper divisors (8993426).

78021889 is an frugal number, since it uses more digits than its factorization.

78021889 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 190 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 43.

The cubic root of 78021889 is about 427.3058320496.

The spelling of 78021889 in words is "seventy-eight million, twenty-one thousand, eight hundred eighty-nine".