1721887 has 2 divisors, whose sum is σ = 1721888. Its totient is φ = 1721886.

The previous prime is 1721857. The next prime is 1721891. The reversal of 1721887 is 7881271.

It is a strong prime.

It is an emirp because it is prime and its reverse (7881271) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1721887 is a prime.

It is a super-3 number, since 3×1721887³ = 15315641648061633309, which contains 333 as substring.

1721887 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1721807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 860943 + 860944.

It is an arithmetic number, because the mean of its divisors is an integer number (860944).

2^1721887 is an apocalyptic number.

1721887 is a deficient number, since it is larger than the sum of its proper divisors (1).

1721887 is an equidigital number, since it uses as much as digits as its factorization.

1721887 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6272, while the sum is 34.

The square root of 1721887 is about 1312.2069196586. The cubic root of 1721887 is about 119.8583281787.

It can be divided in two parts, 17 and 21887, that added together give a square (21904 = 148²).

The spelling of 1721887 in words is "one million, seven hundred twenty-one thousand, eight hundred eighty-seven".