20867239987 has 4 divisors (see below), whose sum is σ = 22764261816. Its totient is φ = 18970218160.

The previous prime is 20867239973. The next prime is 20867239997. The reversal of 20867239987 is 78993276802.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20867239987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20867239997) 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 in 3 ways as a sum of consecutive naturals, for example, 948510898 + ... + 948510919.

It is an arithmetic number, because the mean of its divisors is an integer number (5691065454).

Almost surely, 2^20867239987 is an apocalyptic number.

20867239987 is a deficient number, since it is larger than the sum of its proper divisors (1897021829).

20867239987 is a wasteful number, since it uses less digits than its factorization.

20867239987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1897021828.

The product of its (nonzero) digits is 18289152, while the sum is 61.

The spelling of 20867239987 in words is "twenty billion, eight hundred sixty-seven million, two hundred thirty-nine thousand, nine hundred eighty-seven".