20721771264 has 144 divisors (see below), whose sum is σ = 56823592448. Its totient is φ = 6698889216.

The previous prime is 20721771263. The next prime is 20721771277. The reversal of 20721771264 is 46217712702.

It is not an unprimeable number, because it can be changed into a prime (20721771263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10427679 + ... + 10429665.

Almost surely, 2^20721771264 is an apocalyptic number.

20721771264 is a gapful number since it is divisible by the number (24) 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 20721771264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28411796224).

20721771264 is an abundant number, since it is smaller than the sum of its proper divisors (36101821184).

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

20721771264 is a wasteful number, since it uses less digits than its factorization.

20721771264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2410 (or 2396 counting only the distinct ones).

The product of its (nonzero) digits is 65856, while the sum is 39.

The spelling of 20721771264 in words is "twenty billion, seven hundred twenty-one million, seven hundred seventy-one thousand, two hundred sixty-four".