20404987 has 2 divisors, whose sum is σ = 20404988. Its totient is φ = 20404986.

The previous prime is 20404961. The next prime is 20404991. The reversal of 20404987 is 78940402.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20404987 is a prime.

It is not a weakly prime, because it can be changed into another prime (20404907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10202493 + 10202494.

It is an arithmetic number, because the mean of its divisors is an integer number (10202494).

Almost surely, 2^20404987 is an apocalyptic number.

20404987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20404987 is an equidigital number, since it uses as much as digits as its factorization.

20404987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 16128, while the sum is 34.

The square root of 20404987 is about 4517.1879526980. The cubic root of 20404987 is about 273.2617052381.

The spelling of 20404987 in words is "twenty million, four hundred four thousand, nine hundred eighty-seven".