1921687 has 2 divisors, whose sum is σ = 1921688. Its totient is φ = 1921686.

The previous prime is 1921681. The next prime is 1921691. The reversal of 1921687 is 7861291.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1921687 - 2⁷ = 1921559 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1921681) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 960843 + 960844.

It is an arithmetic number, because the mean of its divisors is an integer number (960844).

2^1921687 is an apocalyptic number.

1921687 is a deficient number, since it is larger than the sum of its proper divisors (1).

1921687 is an equidigital number, since it uses as much as digits as its factorization.

1921687 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 34.

The square root of 1921687 is about 1386.2492560864. The cubic root of 1921687 is about 124.3256916738.

The spelling of 1921687 in words is "one million, nine hundred twenty-one thousand, six hundred eighty-seven".