2187386781 has 4 divisors (see below), whose sum is σ = 2916515712. Its totient is φ = 1458257852.

The previous prime is 2187386771. The next prime is 2187386801. The reversal of 2187386781 is 1876837812.

2187386781 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

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 2187386781 - 2⁵ = 2187386749 is a prime.

It is a super-2 number, since 2×2187386781² = 9569321859387083922, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2187386711) 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, 364564461 + ... + 364564466.

It is an arithmetic number, because the mean of its divisors is an integer number (729128928).

Almost surely, 2^2187386781 is an apocalyptic number.

It is an amenable number.

2187386781 is a deficient number, since it is larger than the sum of its proper divisors (729128931).

2187386781 is an equidigital number, since it uses as much as digits as its factorization.

2187386781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 729128930.

The product of its digits is 903168, while the sum is 51.

The square root of 2187386781 is about 46769.5069569907. The cubic root of 2187386781 is about 1298.1011293053.

The spelling of 2187386781 in words is "two billion, one hundred eighty-seven million, three hundred eighty-six thousand, seven hundred eighty-one".