2125728820661 has 4 divisors (see below), whose sum is σ = 2126691998592. Its totient is φ = 2124765642732.

The previous prime is 2125728820643. The next prime is 2125728820673. The reversal of 2125728820661 is 1660288275212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 2125728820661 - 2¹⁰ = 2125728819637 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2125728820601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 481585655 + ... + 481590068.

It is an arithmetic number, because the mean of its divisors is an integer number (531672999648).

Almost surely, 2^{2125728820661} is an apocalyptic number.

It is an amenable number.

2125728820661 is a deficient number, since it is larger than the sum of its proper divisors (963177931).

2125728820661 is an equidigital number, since it uses as much as digits as its factorization.

2125728820661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 963177930.

The product of its (nonzero) digits is 1290240, while the sum is 50.

The spelling of 2125728820661 in words is "two trillion, one hundred twenty-five billion, seven hundred twenty-eight million, eight hundred twenty thousand, six hundred sixty-one".