1690421 has 2 divisors, whose sum is σ = 1690422. Its totient is φ = 1690420.

The previous prime is 1690393. The next prime is 1690427. The reversal of 1690421 is 1240961.

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., 1661521 + 28900 = 1289^2 + 170^2 .

It is a cyclic number.

It is not a de Polignac number, because 1690421 - 2⁶ = 1690357 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1690427) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 845210 + 845211.

It is an arithmetic number, because the mean of its divisors is an integer number (845211).

2^1690421 is an apocalyptic number.

It is an amenable number.

1690421 is a deficient number, since it is larger than the sum of its proper divisors (1).

1690421 is an equidigital number, since it uses as much as digits as its factorization.

1690421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 1690421 is about 1300.1619129939. The cubic root of 1690421 is about 119.1237326112.

The spelling of 1690421 in words is "one million, six hundred ninety thousand, four hundred twenty-one".