691977 has 16 divisors (see below), whose sum is σ = 1084608. Its totient is φ = 386880.

The previous prime is 691973. The next prime is 691979. The reversal of 691977 is 779196.

It is not a de Polignac number, because 691977 - 2² = 691973 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 691977.

It is not an unprimeable number, because it can be changed into a prime (691973) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 378 + ... + 1235.

It is an arithmetic number, because the mean of its divisors is an integer number (67788).

2⁶⁹¹⁹⁷⁷ is an apocalyptic number.

It is an amenable number.

691977 is a deficient number, since it is larger than the sum of its proper divisors (392631).

691977 is a wasteful number, since it uses less digits than its factorization.

691977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1640.

The product of its digits is 23814, while the sum is 39.

The square root of 691977 is about 831.8515492562. The cubic root of 691977 is about 88.4498742606.

It can be divided in two parts, 6919 and 77, that added together give a palindrome (6996).

The spelling of 691977 in words is "six hundred ninety-one thousand, nine hundred seventy-seven".