551691 has 30 divisors (see below), whose sum is σ = 965580. Its totient is φ = 312984.

The previous prime is 551689. The next prime is 551693. The reversal of 551691 is 196155.

It is an interprime number because it is at equal distance from previous prime (551689) and next prime (551693).

It is not a de Polignac number, because 551691 - 2¹ = 551689 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 551691.

It is not an unprimeable number, because it can be changed into a prime (551693) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 3900 + ... + 4038.

It is an arithmetic number, because the mean of its divisors is an integer number (32186).

2⁵⁵¹⁶⁹¹ is an apocalyptic number.

551691 is a deficient number, since it is larger than the sum of its proper divisors (413889).

551691 is a wasteful number, since it uses less digits than its factorization.

551691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165 (or 149 counting only the distinct ones).

The product of its digits is 1350, while the sum is 27.

The square root of 551691 is about 742.7590457208. The cubic root of 551691 is about 82.0160091685.

The spelling of 551691 in words is "five hundred fifty-one thousand, six hundred ninety-one".