1851000021 has 12 divisors (see below), whose sum is σ = 2879333548. Its totient is φ = 1139076864.

The previous prime is 1850999993. The next prime is 1851000061. The reversal of 1851000021 is 1200001581.

It can be written as a sum of positive squares in 2 ways, for example, as 605898225 + 1245101796 = 24615^2 + 35286^2 .

It is not a de Polignac number, because 1851000021 - 2⁵ = 1850999989 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1850999958 and 1851000003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1851000061) 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, 7910140 + ... + 7910373.

Almost surely, 2^1851000021 is an apocalyptic number.

It is an amenable number.

1851000021 is a deficient number, since it is larger than the sum of its proper divisors (1028333527).

1851000021 is a wasteful number, since it uses less digits than its factorization.

1851000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15820532 (or 15820529 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 1851000021 is about 43023.2497726520. The cubic root of 1851000021 is about 1227.8221803676.

The spelling of 1851000021 in words is "one billion, eight hundred fifty-one million, twenty-one", and thus it is an aban number.