20987171089 has 16 divisors (see below), whose sum is σ = 22234189824. Its totient is φ = 19782680400.

The previous prime is 20987171087. The next prime is 20987171099. The reversal of 20987171089 is 98017178902.

It is a cyclic number.

It is not a de Polignac number, because 20987171089 - 2¹ = 20987171087 is a prime.

It is a super-2 number, since 2×20987171089² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20987171081) 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 15 ways as a sum of consecutive naturals, for example, 125242 + ... + 240124.

It is an arithmetic number, because the mean of its divisors is an integer number (1389636864).

Almost surely, 2^20987171089 is an apocalyptic number.

It is an amenable number.

20987171089 is a deficient number, since it is larger than the sum of its proper divisors (1247018735).

20987171089 is a wasteful number, since it uses less digits than its factorization.

20987171089 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115068.

The product of its (nonzero) digits is 508032, while the sum is 52.

The spelling of 20987171089 in words is "twenty billion, nine hundred eighty-seven million, one hundred seventy-one thousand, eighty-nine".