1851426721 has 2 divisors, whose sum is σ = 1851426722. Its totient is φ = 1851426720.

The previous prime is 1851426719. The next prime is 1851426779. The reversal of 1851426721 is 1276241581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1823717025 + 27709696 = 42705^2 + 5264^2 .

It is a cyclic number.

It is not a de Polignac number, because 1851426721 - 2¹ = 1851426719 is a prime.

Together with 1851426719, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (1851496721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 925713360 + 925713361.

It is an arithmetic number, because the mean of its divisors is an integer number (925713361).

Almost surely, 2^1851426721 is an apocalyptic number.

It is an amenable number.

1851426721 is a deficient number, since it is larger than the sum of its proper divisors (1).

1851426721 is an equidigital number, since it uses as much as digits as its factorization.

1851426721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26880, while the sum is 37.

The square root of 1851426721 is about 43028.2084335381. The cubic root of 1851426721 is about 1227.9165206279.

The spelling of 1851426721 in words is "one billion, eight hundred fifty-one million, four hundred twenty-six thousand, seven hundred twenty-one".