1393427781 has 6 divisors (see below), whose sum is σ = 2012729030. Its totient is φ = 928951848.

The previous prime is 1393427779. The next prime is 1393427809. The reversal of 1393427781 is 1877243931.

It can be written as a sum of positive squares in only one way, i.e., 1090980900 + 302446881 = 33030^2 + 17391^2 .

It is not a de Polignac number, because 1393427781 - 2¹ = 1393427779 is a prime.

It is a super-2 number, since 2×1393427781² = 3883281961725167922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1393427701) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 77412646 + ... + 77412663.

Almost surely, 2^1393427781 is an apocalyptic number.

It is an amenable number.

1393427781 is a deficient number, since it is larger than the sum of its proper divisors (619301249).

1393427781 is a wasteful number, since it uses less digits than its factorization.

1393427781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154825315 (or 154825312 counting only the distinct ones).

The product of its digits is 254016, while the sum is 45.

The square root of 1393427781 is about 37328.6455821799. The cubic root of 1393427781 is about 1116.9356554735.

The spelling of 1393427781 in words is "one billion, three hundred ninety-three million, four hundred twenty-seven thousand, seven hundred eighty-one".