2181256901 has 2 divisors, whose sum is σ = 2181256902. Its totient is φ = 2181256900.

The previous prime is 2181256807. The next prime is 2181256919. The reversal of 2181256901 is 1096521812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1776201025 + 405055876 = 42145^2 + 20126^2 .

It is a cyclic number.

It is not a de Polignac number, because 2181256901 - 2²² = 2177062597 is a prime.

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

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2181256001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1090628450 + 1090628451.

It is an arithmetic number, because the mean of its divisors is an integer number (1090628451).

Almost surely, 2^2181256901 is an apocalyptic number.

It is an amenable number.

2181256901 is a deficient number, since it is larger than the sum of its proper divisors (1).

2181256901 is an equidigital number, since it uses as much as digits as its factorization.

2181256901 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 8640, while the sum is 35.

The square root of 2181256901 is about 46703.9281110272. The cubic root of 2181256901 is about 1296.8874057214.

The spelling of 2181256901 in words is "two billion, one hundred eighty-one million, two hundred fifty-six thousand, nine hundred one".