1901209 has 2 divisors, whose sum is σ = 1901210. Its totient is φ = 1901208.

The previous prime is 1901201. The next prime is 1901219. The reversal of 1901209 is 9021091.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1537600 + 363609 = 1240^2 + 603^2 .

It is a cyclic number.

It is not a de Polignac number, because 1901209 - 2³ = 1901201 is a prime.

It is a super-2 number, since 2×1901209² = 7229191323362, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1901209.

It is not a weakly prime, because it can be changed into another prime (1901201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 950604 + 950605.

It is an arithmetic number, because the mean of its divisors is an integer number (950605).

2^1901209 is an apocalyptic number.

It is an amenable number.

1901209 is a deficient number, since it is larger than the sum of its proper divisors (1).

1901209 is an equidigital number, since it uses as much as digits as its factorization.

1901209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 162, while the sum is 22.

The square root of 1901209 is about 1378.8433558603. The cubic root of 1901209 is about 123.8824979517.

The spelling of 1901209 in words is "one million, nine hundred one thousand, two hundred nine".