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1987891 is a prime number
BaseRepresentation
bin111100101010100110011
310201222212121
413211110303
51002103031
6110335111
722616413
oct7452463
93658777
101987891
111138594
127ba497
13547a89
1439a643
15294011
hex1e5533

1987891 has 2 divisors, whose sum is σ = 1987892. Its totient is φ = 1987890.

The previous prime is 1987889. The next prime is 1987901.

1987891 is nontrivially palindromic in base 10.

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 1987891 - 21 = 1987889 is a prime.

Together with 1987889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1987841) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993945 + 993946.

It is an arithmetic number, because the mean of its divisors is an integer number (993946).

21987891 is an apocalyptic number.

1987891 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987891 is an equidigital number, since it uses as much as digits as its factorization.

1987891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 43.

The square root of 1987891 is about 1409.9258845769. The cubic root of 1987891 is about 125.7373170244.

The spelling of 1987891 in words is "one million, nine hundred eighty-seven thousand, eight hundred ninety-one".