690841421 has 2 divisors, whose sum is σ = 690841422. Its totient is φ = 690841420.

The previous prime is 690841357. The next prime is 690841423. The reversal of 690841421 is 124148096.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 576672196 + 114169225 = 24014^2 + 10685^2 .

It is a cyclic number.

It is not a de Polignac number, because 690841421 - 2⁶ = 690841357 is a prime.

Together with 690841423, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (690841423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345420710 + 345420711.

It is an arithmetic number, because the mean of its divisors is an integer number (345420711).

Almost surely, 2^690841421 is an apocalyptic number.

It is an amenable number.

690841421 is a deficient number, since it is larger than the sum of its proper divisors (1).

690841421 is an equidigital number, since it uses as much as digits as its factorization.

690841421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13824, while the sum is 35.

The square root of 690841421 is about 26283.8623683811. The cubic root of 690841421 is about 884.0146378179.

The spelling of 690841421 in words is "six hundred ninety million, eight hundred forty-one thousand, four hundred twenty-one".