1690621 has 2 divisors, whose sum is σ = 1690622. Its totient is φ = 1690620.

The previous prime is 1690609. The next prime is 1690651. The reversal of 1690621 is 1260961.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1179396 + 511225 = 1086^2 + 715^2 .

It is a cyclic number.

It is not a de Polignac number, because 1690621 - 2¹¹ = 1688573 is a prime.

It is equal to p₁₂₇₄₇₄ and since 1690621 and 127474 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1690651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 845310 + 845311.

It is an arithmetic number, because the mean of its divisors is an integer number (845311).

2^1690621 is an apocalyptic number.

It is an amenable number.

1690621 is a deficient number, since it is larger than the sum of its proper divisors (1).

1690621 is an equidigital number, since it uses as much as digits as its factorization.

1690621 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 1690621 is about 1300.2388242165. The cubic root of 1690621 is about 119.1284304167.

The spelling of 1690621 in words is "one million, six hundred ninety thousand, six hundred twenty-one".