20785408581 has 48 divisors (see below), whose sum is σ = 34731376640. Its totient is φ = 10818005760.

The previous prime is 20785408561. The next prime is 20785408619. The reversal of 20785408581 is 18580458702.

It is not a de Polignac number, because 20785408581 - 2⁶ = 20785408517 is a prime.

It is a super-3 number, since 3×20785408581³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20785408581.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20785408561) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 132900 + ... + 243378.

Almost surely, 2^20785408581 is an apocalyptic number.

20785408581 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20785408581 is a deficient number, since it is larger than the sum of its proper divisors (13945968059).

20785408581 is a wasteful number, since it uses less digits than its factorization.

20785408581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110554 (or 110537 counting only the distinct ones).

The product of its (nonzero) digits is 716800, while the sum is 48.

The spelling of 20785408581 in words is "twenty billion, seven hundred eighty-five million, four hundred eight thousand, five hundred eighty-one".