20660987 has 2 divisors, whose sum is σ = 20660988. Its totient is φ = 20660986.

The previous prime is 20660977. The next prime is 20660989. The reversal of 20660987 is 78906602.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20660987 is a prime.

Together with 20660989, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20660987.

It is not a weakly prime, because it can be changed into another prime (20660989) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10330493 + 10330494.

It is an arithmetic number, because the mean of its divisors is an integer number (10330494).

Almost surely, 2^20660987 is an apocalyptic number.

20660987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20660987 is an equidigital number, since it uses as much as digits as its factorization.

20660987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 36288, while the sum is 38.

The square root of 20660987 is about 4545.4358426888. The cubic root of 20660987 is about 274.3997353354.

The spelling of 20660987 in words is "twenty million, six hundred sixty thousand, nine hundred eighty-seven".