20561655000 has 320 divisors, whose sum is σ = 67775304960. Its totient is φ = 5186368000.

The previous prime is 20561654969. The next prime is 20561655007. The reversal of 20561655000 is 55616502.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20561655007) 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 79 ways as a sum of consecutive naturals, for example, 36914722 + ... + 36915278.

It is an arithmetic number, because the mean of its divisors is an integer number (211797828).

Almost surely, 2^20561655000 is an apocalyptic number.

20561655000 is a gapful number since it is divisible by the number (20) 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 20561655000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33887652480).

20561655000 is an abundant number, since it is smaller than the sum of its proper divisors (47213649960).

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

20561655000 is a wasteful number, since it uses less digits than its factorization.

20561655000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 716 (or 697 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 30.

The spelling of 20561655000 in words is "twenty billion, five hundred sixty-one million, six hundred fifty-five thousand".