1355782781 has 2 divisors, whose sum is σ = 1355782782. Its totient is φ = 1355782780.

The previous prime is 1355782751. The next prime is 1355782783. The reversal of 1355782781 is 1872875531.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1336999225 + 18783556 = 36565^2 + 4334^2 .

It is a cyclic number.

It is not a de Polignac number, because 1355782781 - 2¹⁸ = 1355520637 is a prime.

It is a super-2 number, since 2×1355782781² = 3676293898512187922, which contains 22 as substring.

Together with 1355782783, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1355782783) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 677891390 + 677891391.

It is an arithmetic number, because the mean of its divisors is an integer number (677891391).

Almost surely, 2^1355782781 is an apocalyptic number.

It is an amenable number.

1355782781 is a deficient number, since it is larger than the sum of its proper divisors (1).

1355782781 is an equidigital number, since it uses as much as digits as its factorization.

1355782781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 470400, while the sum is 47.

The square root of 1355782781 is about 36820.9557317569. The cubic root of 1355782781 is about 1106.7852718703.

The spelling of 1355782781 in words is "one billion, three hundred fifty-five million, seven hundred eighty-two thousand, seven hundred eighty-one".