690388821 has 24 divisors (see below), whose sum is σ = 1012078080. Its totient is φ = 453432096.

The previous prime is 690388799. The next prime is 690388841. The reversal of 690388821 is 128883096.

It is not a de Polignac number, because 690388821 - 2⁶ = 690388757 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (690388841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 463540 + ... + 465026.

It is an arithmetic number, because the mean of its divisors is an integer number (42169920).

Almost surely, 2^690388821 is an apocalyptic number.

It is an amenable number.

690388821 is a deficient number, since it is larger than the sum of its proper divisors (321689259).

690388821 is a wasteful number, since it uses less digits than its factorization.

690388821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2225 (or 2222 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The square root of 690388821 is about 26275.2511120256. The cubic root of 690388821 is about 883.8215436093.

The spelling of 690388821 in words is "six hundred ninety million, three hundred eighty-eight thousand, eight hundred twenty-one".