21517101947420 has 96 divisors (see below), whose sum is σ = 49392887201280. Its totient is φ = 7838354718720.

The previous prime is 21517101947377. The next prime is 21517101947503. The reversal of 21517101947420 is 2474910171512.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 96192266 + ... + 96415694.

It is an arithmetic number, because the mean of its divisors is an integer number (514509241680).

Almost surely, 2^{21517101947420} is an apocalyptic number.

21517101947420 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 21517101947420, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24696443600640).

21517101947420 is an abundant number, since it is smaller than the sum of its proper divisors (27875785253860).

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

21517101947420 is a wasteful number, since it uses less digits than its factorization.

21517101947420 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 232623 (or 232621 counting only the distinct ones).

The product of its (nonzero) digits is 141120, while the sum is 44.

The spelling of 21517101947420 in words is "twenty-one trillion, five hundred seventeen billion, one hundred one million, nine hundred forty-seven thousand, four hundred twenty".