1845720721 has 16 divisors (see below), whose sum is σ = 2075802624. Its totient is φ = 1628345664.

The previous prime is 1845720703. The next prime is 1845720761. The reversal of 1845720721 is 1270275481.

It is a cyclic number.

It is not a de Polignac number, because 1845720721 - 2⁷ = 1845720593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1845720761) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 658495 + ... + 661291.

It is an arithmetic number, because the mean of its divisors is an integer number (129737664).

Almost surely, 2^1845720721 is an apocalyptic number.

It is an amenable number.

1845720721 is a deficient number, since it is larger than the sum of its proper divisors (230081903).

1845720721 is a wasteful number, since it uses less digits than its factorization.

1845720721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5040.

The product of its (nonzero) digits is 31360, while the sum is 37.

The square root of 1845720721 is about 42961.8519270294. The cubic root of 1845720721 is about 1226.6537643948.

The spelling of 1845720721 in words is "one billion, eight hundred forty-five million, seven hundred twenty thousand, seven hundred twenty-one".