1987121 has 2 divisors, whose sum is σ = 1987122. Its totient is φ = 1987120.

The previous prime is 1987099. The next prime is 1987123. The reversal of 1987121 is 1217891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1288225 + 698896 = 1135^2 + 836^2 .

It is a cyclic number.

It is not a de Polignac number, because 1987121 - 2⁶ = 1987057 is a prime.

Together with 1987123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (1987123) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 993560 + 993561.

It is an arithmetic number, because the mean of its divisors is an integer number (993561).

2^1987121 is an apocalyptic number.

It is an amenable number.

1987121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1987121 is an equidigital number, since it uses as much as digits as its factorization.

1987121 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1008, while the sum is 29.

The square root of 1987121 is about 1409.6527941305. The cubic root of 1987121 is about 125.7210803465.

The spelling of 1987121 in words is "one million, nine hundred eighty-seven thousand, one hundred twenty-one".