1396649781 has 12 divisors (see below), whose sum is σ = 2017827552. Its totient is φ = 930894696.

The previous prime is 1396649759. The next prime is 1396649783. The reversal of 1396649781 is 1879466931.

1396649781 is a `hidden beast` number, since 13 + 9 + 66 + 497 + 81 = 666.

It is not a de Polignac number, because 1396649781 - 2¹⁸ = 1396387637 is a prime.

It is a super-2 number, since 2×1396649781² = 3901261221534695922, which contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1396649783) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 34080 + ... + 62886.

It is an arithmetic number, because the mean of its divisors is an integer number (168152296).

Almost surely, 2^1396649781 is an apocalyptic number.

It is an amenable number.

1396649781 is a deficient number, since it is larger than the sum of its proper divisors (621177771).

1396649781 is a wasteful number, since it uses less digits than its factorization.

1396649781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34200 (or 34197 counting only the distinct ones).

The product of its digits is 1959552, while the sum is 54.

The square root of 1396649781 is about 37371.7778677975. Note that the first 3 decimals coincide. The cubic root of 1396649781 is about 1117.7958833947.

The spelling of 1396649781 in words is "one billion, three hundred ninety-six million, six hundred forty-nine thousand, seven hundred eighty-one".