2129861 has 2 divisors, whose sum is σ = 2129862. Its totient is φ = 2129860.

The previous prime is 2129851. The next prime is 2129867. The reversal of 2129861 is 1689212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1612900 + 516961 = 1270^2 + 719^2 .

It is a cyclic number.

It is not a de Polignac number, because 2129861 - 2⁶ = 2129797 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2129867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1064930 + 1064931.

It is an arithmetic number, because the mean of its divisors is an integer number (1064931).

2^2129861 is an apocalyptic number.

It is an amenable number.

2129861 is a deficient number, since it is larger than the sum of its proper divisors (1).

2129861 is an equidigital number, since it uses as much as digits as its factorization.

2129861 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 29.

The square root of 2129861 is about 1459.4043305404. The cubic root of 2129861 is about 128.6620362490.

The spelling of 2129861 in words is "two million, one hundred twenty-nine thousand, eight hundred sixty-one".