689243021 has 2 divisors, whose sum is σ = 689243022. Its totient is φ = 689243020.

The previous prime is 689242999. The next prime is 689243033. The reversal of 689243021 is 120342986.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 515925796 + 173317225 = 22714^2 + 13165^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-689243021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (689243081) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 344621510 + 344621511.

It is an arithmetic number, because the mean of its divisors is an integer number (344621511).

Almost surely, 2^689243021 is an apocalyptic number.

It is an amenable number.

689243021 is a deficient number, since it is larger than the sum of its proper divisors (1).

689243021 is an equidigital number, since it uses as much as digits as its factorization.

689243021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 689243021 is about 26253.4382700628. The cubic root of 689243021 is about 883.3323296852.

Subtracting from 689243021 its sum of digits (35), we obtain a palindrome (689242986).

The spelling of 689243021 in words is "six hundred eighty-nine million, two hundred forty-three thousand, twenty-one".