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2131991 is a prime number
BaseRepresentation
bin1000001000100000010111
311000022112122
420020200113
51021210431
6113410155
724056501
oct10104027
94008478
102131991
111226884
1286995b
13598544
143d6d71
152c1a7b
hex208817

2131991 has 2 divisors, whose sum is σ = 2131992. Its totient is φ = 2131990.

The previous prime is 2131981. The next prime is 2132003. The reversal of 2131991 is 1991312.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2k-2131991 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a self number, because there is not a number n which added to its sum of digits gives 2131991.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2131951) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1065995 + 1065996.

It is an arithmetic number, because the mean of its divisors is an integer number (1065996).

22131991 is an apocalyptic number.

2131991 is a deficient number, since it is larger than the sum of its proper divisors (1).

2131991 is an equidigital number, since it uses as much as digits as its factorization.

2131991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 486, while the sum is 26.

The square root of 2131991 is about 1460.1338979696. The cubic root of 2131991 is about 128.7049121036.

The spelling of 2131991 in words is "two million, one hundred thirty-one thousand, nine hundred ninety-one".