2121765105720 has 256 divisors, whose sum is σ = 6981428160000. Its totient is φ = 512677693440.

The previous prime is 2121765105697. The next prime is 2121765105727. The reversal of 2121765105720 is 275015671212.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121765105727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 47462499 + ... + 47507181.

It is an arithmetic number, because the mean of its divisors is an integer number (27271203750).

Almost surely, 2^{2121765105720} is an apocalyptic number.

2121765105720 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 2121765105720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3490714080000).

2121765105720 is an abundant number, since it is smaller than the sum of its proper divisors (4859663054280).

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

2121765105720 is a wasteful number, since it uses less digits than its factorization.

2121765105720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45270 (or 45266 counting only the distinct ones).

The product of its (nonzero) digits is 58800, while the sum is 39.

The spelling of 2121765105720 in words is "two trillion, one hundred twenty-one billion, seven hundred sixty-five million, one hundred five thousand, seven hundred twenty".