1551691 has 2 divisors, whose sum is σ = 1551692. Its totient is φ = 1551690.

The previous prime is 1551677. The next prime is 1551701. The reversal of 1551691 is 1961551.

It is a strong prime.

It is an emirp because it is prime and its reverse (1961551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1551691 - 2⁵ = 1551659 is a prime.

It is not a weakly prime, because it can be changed into another prime (1551601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 775845 + 775846.

It is an arithmetic number, because the mean of its divisors is an integer number (775846).

2^1551691 is an apocalyptic number.

1551691 is a deficient number, since it is larger than the sum of its proper divisors (1).

1551691 is an equidigital number, since it uses as much as digits as its factorization.

1551691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1350, while the sum is 28.

The square root of 1551691 is about 1245.6688966174. The cubic root of 1551691 is about 115.7715231308.

The spelling of 1551691 in words is "one million, five hundred fifty-one thousand, six hundred ninety-one".