20511561540 has 48 divisors (see below), whose sum is σ = 57438662400. Its totient is φ = 5469150720.

The previous prime is 20511561523. The next prime is 20511561547. The reversal of 20511561540 is 4516511502.

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

It is a junction number, because it is equal to n+sod(n) for n = 20511561498 and 20511561507.

It is not an unprimeable number, because it can be changed into a prime (20511561547) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 936636 + ... + 958284.

It is an arithmetic number, because the mean of its divisors is an integer number (1196638800).

Almost surely, 2^20511561540 is an apocalyptic number.

20511561540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20511561540 is an abundant number, since it is smaller than the sum of its proper divisors (36927100860).

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

20511561540 is a wasteful number, since it uses less digits than its factorization.

20511561540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37452 (or 37450 counting only the distinct ones).

The product of its (nonzero) digits is 6000, while the sum is 30.

The spelling of 20511561540 in words is "twenty billion, five hundred eleven million, five hundred sixty-one thousand, five hundred forty".