1978687 has 2 divisors, whose sum is σ = 1978688. Its totient is φ = 1978686.

The previous prime is 1978673. The next prime is 1978693. The reversal of 1978687 is 7868791.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1978687 - 2¹⁵ = 1945919 is a prime.

It is a super-4 number, since 4×1978687⁴ (a number of 26 digits) contains 4444 as substring.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1978087) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 989343 + 989344.

It is an arithmetic number, because the mean of its divisors is an integer number (989344).

2^1978687 is an apocalyptic number.

1978687 is a deficient number, since it is larger than the sum of its proper divisors (1).

1978687 is an equidigital number, since it uses as much as digits as its factorization.

1978687 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 169344, while the sum is 46.

The square root of 1978687 is about 1406.6580963404. The cubic root of 1978687 is about 125.5429608004.

The spelling of 1978687 in words is "one million, nine hundred seventy-eight thousand, six hundred eighty-seven".