20356771987 has 2 divisors, whose sum is σ = 20356771988. Its totient is φ = 20356771986.

The previous prime is 20356771951. The next prime is 20356771997. The reversal of 20356771987 is 78917765302.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20356771987 - 2⁷ = 20356771859 is a prime.

It is not a weakly prime, because it can be changed into another prime (20356771997) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10178385993 + 10178385994.

It is an arithmetic number, because the mean of its divisors is an integer number (10178385994).

Almost surely, 2^20356771987 is an apocalyptic number.

20356771987 is a deficient number, since it is larger than the sum of its proper divisors (1).

20356771987 is an equidigital number, since it uses as much as digits as its factorization.

20356771987 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4445280, while the sum is 55.

The spelling of 20356771987 in words is "twenty billion, three hundred fifty-six million, seven hundred seventy-one thousand, nine hundred eighty-seven".