690521 has 4 divisors (see below), whose sum is σ = 743652. Its totient is φ = 637392.

The previous prime is 690511. The next prime is 690533. The reversal of 690521 is 125096.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 403225 + 287296 = 635^2 + 536^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-690521 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 690521.

It is not an unprimeable number, because it can be changed into a prime (690511) 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, 26546 + ... + 26571.

It is an arithmetic number, because the mean of its divisors is an integer number (185913).

2⁶⁹⁰⁵²¹ is an apocalyptic number.

It is an amenable number.

690521 is a deficient number, since it is larger than the sum of its proper divisors (53131).

690521 is a wasteful number, since it uses less digits than its factorization.

690521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53130.

The product of its (nonzero) digits is 540, while the sum is 23.

The square root of 690521 is about 830.9759322628. The cubic root of 690521 is about 88.3877944287.

The spelling of 690521 in words is "six hundred ninety thousand, five hundred twenty-one".