1391681 has 8 divisors (see below), whose sum is σ = 1479720. Its totient is φ = 1306368.

The previous prime is 1391669. The next prime is 1391701. The reversal of 1391681 is 1861931.

It is a happy number.

1391681 is an esthetic number in base 6, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in 4 ways, for example, as 982081 + 409600 = 991^2 + 640^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1391681 is a prime.

It is a super-2 number, since 2×1391681² = 3873552011522, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a Duffinian number.

1391681 is an undulating number in base 6.

It is not an unprimeable number, because it can be changed into a prime (1391641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 425 + ... + 1721.

It is an arithmetic number, because the mean of its divisors is an integer number (184965).

2^1391681 is an apocalyptic number.

It is an amenable number.

1391681 is a deficient number, since it is larger than the sum of its proper divisors (88039).

1391681 is a wasteful number, since it uses less digits than its factorization.

1391681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1363.

The product of its digits is 1296, while the sum is 29.

The square root of 1391681 is about 1179.6952996431. The cubic root of 1391681 is about 111.6468735493.

The spelling of 1391681 in words is "one million, three hundred ninety-one thousand, six hundred eighty-one".