691057 has 4 divisors (see below), whose sum is σ = 693616. Its totient is φ = 688500.

The previous prime is 691051. The next prime is 691063. The reversal of 691057 is 750196.

It is a happy number.

691057 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (691051) and next prime (691063).

It is a cyclic number.

It is not a de Polignac number, because 691057 - 2⁷ = 690929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (691051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 819 + ... + 1432.

It is an arithmetic number, because the mean of its divisors is an integer number (173404).

2⁶⁹¹⁰⁵⁷ is an apocalyptic number.

It is an amenable number.

691057 is a deficient number, since it is larger than the sum of its proper divisors (2559).

691057 is a wasteful number, since it uses less digits than its factorization.

691057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2558.

The product of its (nonzero) digits is 1890, while the sum is 28.

The square root of 691057 is about 831.2983820506. The cubic root of 691057 is about 88.4106581336.

The spelling of 691057 in words is "six hundred ninety-one thousand, fifty-seven".