2121756765 has 16 divisors (see below), whose sum is σ = 3477612096. Its totient is φ = 1104003200.

The previous prime is 2121756751. The next prime is 2121756781. The reversal of 2121756765 is 5676571212.

It is a happy number.

It is not a de Polignac number, because 2121756765 - 2⁶ = 2121756701 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1724391 + ... + 1725620.

It is an arithmetic number, because the mean of its divisors is an integer number (217350756).

Almost surely, 2^2121756765 is an apocalyptic number.

It is an amenable number.

2121756765 is a deficient number, since it is larger than the sum of its proper divisors (1355855331).

2121756765 is a wasteful number, since it uses less digits than its factorization.

2121756765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3450060.

The product of its digits is 176400, while the sum is 42.

The square root of 2121756765 is about 46062.5310311971. The cubic root of 2121756765 is about 1284.9864018708.

The spelling of 2121756765 in words is "two billion, one hundred twenty-one million, seven hundred fifty-six thousand, seven hundred sixty-five".