20721295447440 has 320 divisors, whose sum is σ = 75303066009600. Its totient is φ = 4711495165440.

The previous prime is 20721295447423. The next prime is 20721295447469. The reversal of 20721295447440 is 4474459212702.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 15064177 + ... + 16382063.

It is an arithmetic number, because the mean of its divisors is an integer number (235322081280).

Almost surely, 2^{20721295447440} is an apocalyptic number.

20721295447440 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 20721295447440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (37651533004800).

20721295447440 is an abundant number, since it is smaller than the sum of its proper divisors (54581770562160).

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

20721295447440 is a wasteful number, since it uses less digits than its factorization.

20721295447440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1318115 (or 1318095 counting only the distinct ones).

The product of its (nonzero) digits is 4515840, while the sum is 51.

The spelling of 20721295447440 in words is "twenty trillion, seven hundred twenty-one billion, two hundred ninety-five million, four hundred forty-seven thousand, four hundred forty".