386643781 has 2 divisors, whose sum is σ = 386643782. Its totient is φ = 386643780.

The previous prime is 386643779. The next prime is 386643791. The reversal of 386643781 is 187346683.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 358913025 + 27730756 = 18945^2 + 5266^2 .

It is a cyclic number.

It is not a de Polignac number, because 386643781 - 2¹ = 386643779 is a prime.

It is a super-2 number, since 2×386643781² = 298986826771951922, which contains 22 as substring.

Together with 386643779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (386643701) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 193321890 + 193321891.

It is an arithmetic number, because the mean of its divisors is an integer number (193321891).

Almost surely, 2^386643781 is an apocalyptic number.

It is an amenable number.

386643781 is a deficient number, since it is larger than the sum of its proper divisors (1).

386643781 is an equidigital number, since it uses as much as digits as its factorization.

386643781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 580608, while the sum is 46.

The square root of 386643781 is about 19663.2596738181. The cubic root of 386643781 is about 728.5125030299.

The spelling of 386643781 in words is "three hundred eighty-six million, six hundred forty-three thousand, seven hundred eighty-one".