213778645 has 4 divisors (see below), whose sum is σ = 256534380. Its totient is φ = 171022912.

The previous prime is 213778639. The next prime is 213778651. The reversal of 213778645 is 546877312.

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

It is an interprime number because it is at equal distance from previous prime (213778639) and next prime (213778651).

It can be written as a sum of positive squares in 2 ways, for example, as 29008996 + 184769649 = 5386^2 + 13593^2 .

It is a cyclic number.

It is not a de Polignac number, because 213778645 - 2¹⁷ = 213647573 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21377860 + ... + 21377869.

It is an arithmetic number, because the mean of its divisors is an integer number (64133595).

Almost surely, 2^213778645 is an apocalyptic number.

It is an amenable number.

213778645 is a deficient number, since it is larger than the sum of its proper divisors (42755735).

213778645 is an equidigital number, since it uses as much as digits as its factorization.

213778645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42755734.

The product of its digits is 282240, while the sum is 43.

The square root of 213778645 is about 14621.1711227247. The cubic root of 213778645 is about 597.9360984726.

The spelling of 213778645 in words is "two hundred thirteen million, seven hundred seventy-eight thousand, six hundred forty-five".