1999021 has 2 divisors, whose sum is σ = 1999022. Its totient is φ = 1999020.

The previous prime is 1999007. The next prime is 1999033. The reversal of 1999021 is 1209991.

1999021 is nontrivially palindromic in base 4.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1990921 + 8100 = 1411^2 + 90^2 .

It is a cyclic number.

It is not a de Polignac number, because 1999021 - 2¹³ = 1990829 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999510 + 999511.

It is an arithmetic number, because the mean of its divisors is an integer number (999511).

2^1999021 is an apocalyptic number.

It is an amenable number.

1999021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999021 is an equidigital number, since it uses as much as digits as its factorization.

1999021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1458, while the sum is 31.

The square root of 1999021 is about 1413.8673912358. The cubic root of 1999021 is about 125.9715439224.

The spelling of 1999021 in words is "one million, nine hundred ninety-nine thousand, twenty-one".