20761987 has 2 divisors, whose sum is σ = 20761988. Its totient is φ = 20761986.

The previous prime is 20761973. The next prime is 20761997. The reversal of 20761987 is 78916702.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20761987 - 2⁷ = 20761859 is a prime.

It is not a weakly prime, because it can be changed into another prime (20761907) 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, 10380993 + 10380994.

It is an arithmetic number, because the mean of its divisors is an integer number (10380994).

Almost surely, 2^20761987 is an apocalyptic number.

20761987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20761987 is an equidigital number, since it uses as much as digits as its factorization.

20761987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 20761987 is about 4556.5323437895. The cubic root of 20761987 is about 274.8461376216.

The spelling of 20761987 in words is "twenty million, seven hundred sixty-one thousand, nine hundred eighty-seven".