20931087408 has 480 divisors, whose sum is σ = 71491424256. Its totient is φ = 5124672000.

The previous prime is 20931087379. The next prime is 20931087421. The reversal of 20931087408 is 80478013902.

It is a super-2 number, since 2×20931087408² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is a self number, because there is not a number n which added to its sum of digits gives 20931087408.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 252181735 + ... + 252181817.

Almost surely, 2^20931087408 is an apocalyptic number.

20931087408 is a gapful number since it is divisible by the number (28) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20931087408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35745712128).

20931087408 is an abundant number, since it is smaller than the sum of its proper divisors (50560336848).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20931087408 is a wasteful number, since it uses less digits than its factorization.

20931087408 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 245 (or 208 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 42.

The spelling of 20931087408 in words is "twenty billion, nine hundred thirty-one million, eighty-seven thousand, four hundred eight".