3805663557721 has 9 divisors (see below), whose sum is σ = 3811797016191. Its totient is φ = 3799539961992.

The previous prime is 3805663557629. The next prime is 3805663557727. The reversal of 3805663557721 is 1277553665083.

The square root of 3805663557721 is 1950811.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 219806257225 + 3585857300496 = 468835^2 + 1893636^2 .

It is not a de Polignac number, because 3805663557721 - 2¹⁵ = 3805663524953 is a prime.

It is a super-2 number, since 2×3805663557721² (a number of 26 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (3805663557727) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1664040640 + ... + 1664042926.

It is an arithmetic number, because the mean of its divisors is an integer number (423533001799).

Almost surely, 2^{3805663557721} is an apocalyptic number.

3805663557721 is the 1950811-st square number.

3805663557721 is the 975406-th centered octagonal number.

It is an amenable number.

3805663557721 is a deficient number, since it is larger than the sum of its proper divisors (6133458470).

3805663557721 is an frugal number, since it uses more digits than its factorization.

3805663557721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6280 (or 3140 counting only the distinct ones).

The product of its (nonzero) digits is 31752000, while the sum is 58.

The spelling of 3805663557721 in words is "three trillion, eight hundred five billion, six hundred sixty-three million, five hundred fifty-seven thousand, seven hundred twenty-one".