20661266560 has 64 divisors (see below), whose sum is σ = 53883662400. Its totient is φ = 7513185280.

The previous prime is 20661266513. The next prime is 20661266567. The reversal of 20661266560 is 6566216602.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (20661266567) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1460380 + ... + 1474459.

It is an arithmetic number, because the mean of its divisors is an integer number (841932225).

Almost surely, 2^20661266560 is an apocalyptic number.

20661266560 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20661266560 is an abundant number, since it is smaller than the sum of its proper divisors (33222395840).

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

20661266560 is a wasteful number, since it uses less digits than its factorization.

20661266560 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2934869 (or 2934857 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 40.

The spelling of 20661266560 in words is "twenty billion, six hundred sixty-one million, two hundred sixty-six thousand, five hundred sixty".