2121605161720 has 128 divisors (see below), whose sum is σ = 5409509054400. Its totient is φ = 741797683200.

The previous prime is 2121605161703. The next prime is 2121605161721. The reversal of 2121605161720 is 271615061212.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121605161721) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2730202 + ... + 3420118.

Almost surely, 2^{2121605161720} is an apocalyptic number.

2121605161720 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 2121605161720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2704754527200).

2121605161720 is an abundant number, since it is smaller than the sum of its proper divisors (3287903892680).

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

2121605161720 is a wasteful number, since it uses less digits than its factorization.

2121605161720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 690209 (or 690205 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 34.

The spelling of 2121605161720 in words is "two trillion, one hundred twenty-one billion, six hundred five million, one hundred sixty-one thousand, seven hundred twenty".