1664261 has 2 divisors, whose sum is σ = 1664262. Its totient is φ = 1664260.

The previous prime is 1664251. The next prime is 1664279. The reversal of 1664261 is 1624661.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1562500 + 101761 = 1250^2 + 319^2 .

It is an emirp because it is prime and its reverse (1624661) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1664261 is a prime.

It is a super-2 number, since 2×1664261² = 5539529352242, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1664261.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1664251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832130 + 832131.

It is an arithmetic number, because the mean of its divisors is an integer number (832131).

2^1664261 is an apocalyptic number.

It is an amenable number.

1664261 is a deficient number, since it is larger than the sum of its proper divisors (1).

1664261 is an equidigital number, since it uses as much as digits as its factorization.

1664261 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 26.

The square root of 1664261 is about 1290.0624015915. The cubic root of 1664261 is about 118.5060380172.

The spelling of 1664261 in words is "one million, six hundred sixty-four thousand, two hundred sixty-one".