78222421 has 4 divisors (see below), whose sum is σ = 78269292. Its totient is φ = 78175552.

The previous prime is 78222413. The next prime is 78222439. The reversal of 78222421 is 12422287.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 21762225 + 56460196 = 4665^2 + 7514^2 .

It is a cyclic number.

It is not a de Polignac number, because 78222421 - 2³ = 78222413 is a prime.

It is a super-2 number, since 2×78222421² = 12237494294202482, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 78222421.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78222451) 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, 20836 + ... + 24301.

It is an arithmetic number, because the mean of its divisors is an integer number (19567323).

Almost surely, 2^78222421 is an apocalyptic number.

It is an amenable number.

78222421 is a deficient number, since it is larger than the sum of its proper divisors (46871).

78222421 is a wasteful number, since it uses less digits than its factorization.

78222421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46870.

The product of its digits is 3584, while the sum is 28.

The square root of 78222421 is about 8844.3440118530. The cubic root of 78222421 is about 427.6716062642.

The spelling of 78222421 in words is "seventy-eight million, two hundred twenty-two thousand, four hundred twenty-one".