2121566655 has 16 divisors (see below), whose sum is σ = 3655622880. Its totient is φ = 1044463488.

The previous prime is 2121566639. The next prime is 2121566669. The reversal of 2121566655 is 5566651212.

It is a happy number.

It is not a de Polignac number, because 2121566655 - 2⁴ = 2121566639 is a prime.

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

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, 5439720 + ... + 5440109.

It is an arithmetic number, because the mean of its divisors is an integer number (228476430).

Almost surely, 2^2121566655 is an apocalyptic number.

2121566655 is a deficient number, since it is larger than the sum of its proper divisors (1534056225).

2121566655 is a wasteful number, since it uses less digits than its factorization.

2121566655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10879850.

The product of its digits is 108000, while the sum is 39.

The square root of 2121566655 is about 46060.4673771337. The cubic root of 2121566655 is about 1284.9480223441.

The spelling of 2121566655 in words is "two billion, one hundred twenty-one million, five hundred sixty-six thousand, six hundred fifty-five".