2043655721 has 4 divisors (see below), whose sum is σ = 2043778944. Its totient is φ = 2043532500.

The previous prime is 2043655699. The next prime is 2043655727. The reversal of 2043655721 is 1275563402.

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 2043655721 - 2¹⁴ = 2043639337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2043655727) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 31985 + ... + 71486.

It is an arithmetic number, because the mean of its divisors is an integer number (510944736).

Almost surely, 2^2043655721 is an apocalyptic number.

It is an amenable number.

2043655721 is a deficient number, since it is larger than the sum of its proper divisors (123223).

2043655721 is a wasteful number, since it uses less digits than its factorization.

2043655721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123222.

The product of its (nonzero) digits is 50400, while the sum is 35.

The square root of 2043655721 is about 45206.8105599145. The cubic root of 2043655721 is about 1269.0222745316.

The spelling of 2043655721 in words is "two billion, forty-three million, six hundred fifty-five thousand, seven hundred twenty-one".