1866781213 has 4 divisors (see below), whose sum is σ = 2036488608. Its totient is φ = 1697073820.

The previous prime is 1866781201. The next prime is 1866781229. The reversal of 1866781213 is 3121876681.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1866781213 - 2⁹ = 1866780701 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1866781213.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1866781013) 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, 84853681 + ... + 84853702.

It is an arithmetic number, because the mean of its divisors is an integer number (509122152).

Almost surely, 2^1866781213 is an apocalyptic number.

It is an amenable number.

1866781213 is a deficient number, since it is larger than the sum of its proper divisors (169707395).

1866781213 is a wasteful number, since it uses less digits than its factorization.

1866781213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 169707394.

The product of its digits is 96768, while the sum is 43.

The square root of 1866781213 is about 43206.2635852720. The cubic root of 1866781213 is about 1231.3016851778.

The spelling of 1866781213 in words is "one billion, eight hundred sixty-six million, seven hundred eighty-one thousand, two hundred thirteen".