2181731 has 2 divisors, whose sum is σ = 2181732. Its totient is φ = 2181730.

The previous prime is 2181719. The next prime is 2181737. The reversal of 2181731 is 1371812.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2181731 is a prime.

It is a super-2 number, since 2×2181731² = 9519900312722, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 2181697 and 2181706.

It is not a weakly prime, because it can be changed into another prime (2181737) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1090865 + 1090866.

It is an arithmetic number, because the mean of its divisors is an integer number (1090866).

2^2181731 is an apocalyptic number.

2181731 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181731 is an equidigital number, since it uses as much as digits as its factorization.

2181731 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 336, while the sum is 23.

The square root of 2181731 is about 1477.0683802722. The cubic root of 2181731 is about 129.6981358965.

The spelling of 2181731 in words is "two million, one hundred eighty-one thousand, seven hundred thirty-one".