2581656121 has 6 divisors (see below), whose sum is σ = 2837688266. Its totient is φ = 2346960000.

The previous prime is 2581656101. The next prime is 2581656139. The reversal of 2581656121 is 1216561852.

2581656121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 2499500025 + 82156096 = 49995^2 + 9064^2 .

It is not a de Polignac number, because 2581656121 - 2¹⁵ = 2581623353 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2581656101) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 10667880 + ... + 10668121.

Almost surely, 2^2581656121 is an apocalyptic number.

It is an amenable number.

2581656121 is a deficient number, since it is larger than the sum of its proper divisors (256032145).

2581656121 is a wasteful number, since it uses less digits than its factorization.

2581656121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21336023 (or 21336012 counting only the distinct ones).

The product of its digits is 28800, while the sum is 37.

The square root of 2581656121 is about 50810.0002066522. Note that the first 3 decimals coincide. The cubic root of 2581656121 is about 1371.8273732225.

The spelling of 2581656121 in words is "two billion, five hundred eighty-one million, six hundred fifty-six thousand, one hundred twenty-one".