20681957520 has 480 divisors, whose sum is σ = 86264954880. Its totient is φ = 4333409280.

The previous prime is 20681957507. The next prime is 20681957533. The reversal of 20681957520 is 2575918602.

20681957520 is a `hidden beast` number, since 2 + 0 + 68 + 19 + 57 + 520 = 666.

It is an interprime number because it is at equal distance from previous prime (20681957507) and next prime (20681957533).

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

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, 2965077 + ... + 2972043.

It is an arithmetic number, because the mean of its divisors is an integer number (179718656).

Almost surely, 2^20681957520 is an apocalyptic number.

20681957520 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 20681957520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43132477440).

20681957520 is an abundant number, since it is smaller than the sum of its proper divisors (65582997360).

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

20681957520 is a wasteful number, since it uses less digits than its factorization.

20681957520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7043 (or 7034 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 45.

The spelling of 20681957520 in words is "twenty billion, six hundred eighty-one million, nine hundred fifty-seven thousand, five hundred twenty".