2151800781 has 12 divisors (see below), whose sum is σ = 3106742688. Its totient is φ = 1324184784.

The previous prime is 2151800773. The next prime is 2151800837. The reversal of 2151800781 is 1870081512.

It is not a de Polignac number, because 2151800781 - 2³ = 2151800773 is a prime.

It is a super-2 number, since 2×2151800781² = 9260493202224419922, which contains 22 as substring.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2151800701) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2121585 + ... + 2122598.

It is an arithmetic number, because the mean of its divisors is an integer number (258895224).

Almost surely, 2^2151800781 is an apocalyptic number.

It is an amenable number.

2151800781 is a deficient number, since it is larger than the sum of its proper divisors (954941907).

2151800781 is a wasteful number, since it uses less digits than its factorization.

2151800781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4244212 (or 4244199 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 33.

The square root of 2151800781 is about 46387.5067340335. The cubic root of 2151800781 is about 1291.0231213871.

The spelling of 2151800781 in words is "two billion, one hundred fifty-one million, eight hundred thousand, seven hundred eighty-one".