78221887 has 4 divisors (see below), whose sum is σ = 78246000. Its totient is φ = 78197776.

The previous prime is 78221881. The next prime is 78221893. The reversal of 78221887 is 78812287.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 78812287 = 181 ⋅435427.

It is an interprime number because it is at equal distance from previous prime (78221881) and next prime (78221893).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-78221887 is a prime.

It is a super-3 number, since 3×78221887³ (a number of 25 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78221881) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6262 + ... + 13987.

It is an arithmetic number, because the mean of its divisors is an integer number (19561500).

Almost surely, 2^78221887 is an apocalyptic number.

78221887 is a deficient number, since it is larger than the sum of its proper divisors (24113).

78221887 is a wasteful number, since it uses less digits than its factorization.

78221887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24112.

The product of its digits is 100352, while the sum is 43.

The square root of 78221887 is about 8844.3138230165. The cubic root of 78221887 is about 427.6706330686.

The spelling of 78221887 in words is "seventy-eight million, two hundred twenty-one thousand, eight hundred eighty-seven".