20956515840 has 960 divisors, whose sum is σ = 84221609472. Its totient is φ = 4777574400.

The previous prime is 20956515821. The next prime is 20956515851. The reversal of 20956515840 is 4851565902.

20956515840 is a `hidden beast` number, since 2 + 0 + 9 + 5 + 65 + 1 + 584 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (960).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 343549410 + ... + 343549470.

Almost surely, 2^20956515840 is an apocalyptic number.

20956515840 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 20956515840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (42110804736).

20956515840 is an abundant number, since it is smaller than the sum of its proper divisors (63265093632).

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

20956515840 is a wasteful number, since it uses less digits than its factorization.

20956515840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 432000, while the sum is 45.

The spelling of 20956515840 in words is "twenty billion, nine hundred fifty-six million, five hundred fifteen thousand, eight hundred forty".