1621871 has 2 divisors, whose sum is σ = 1621872. Its totient is φ = 1621870.

The previous prime is 1621861. The next prime is 1621877. The reversal of 1621871 is 1781261.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1621871 - 2¹⁸ = 1359727 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1621871.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1621877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 810935 + 810936.

It is an arithmetic number, because the mean of its divisors is an integer number (810936).

2^1621871 is an apocalyptic number.

1621871 is a deficient number, since it is larger than the sum of its proper divisors (1).

1621871 is an equidigital number, since it uses as much as digits as its factorization.

1621871 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 672, while the sum is 26.

The square root of 1621871 is about 1273.5269922542. The cubic root of 1621871 is about 117.4912261443.

The spelling of 1621871 in words is "one million, six hundred twenty-one thousand, eight hundred seventy-one".