2181237551 has 4 divisors (see below), whose sum is σ = 2185523400. Its totient is φ = 2176951704.

The previous prime is 2181237521. The next prime is 2181237571. The reversal of 2181237551 is 1557321812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2181237551 - 2²² = 2177043247 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2181237521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2142161 + ... + 2143178.

It is an arithmetic number, because the mean of its divisors is an integer number (546380850).

Almost surely, 2^2181237551 is an apocalyptic number.

2181237551 is a deficient number, since it is larger than the sum of its proper divisors (4285849).

2181237551 is an equidigital number, since it uses as much as digits as its factorization.

2181237551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4285848.

The product of its digits is 16800, while the sum is 35.

The square root of 2181237551 is about 46703.7209545449. The cubic root of 2181237551 is about 1296.8835708001.

The spelling of 2181237551 in words is "two billion, one hundred eighty-one million, two hundred thirty-seven thousand, five hundred fifty-one".