80205721 has 6 divisors (see below), whose sum is σ = 81591722. Its totient is φ = 78842880.

The previous prime is 80205679. The next prime is 80205731. The reversal of 80205721 is 12750208.

It can be written as a sum of positive squares in only one way, i.e., 57927321 + 22278400 = 7611^2 + 4720^2 .

It is not a de Polignac number, because 80205721 - 2¹³ = 80197529 is a prime.

It is a super-2 number, since 2×80205721² = 12865915362259682, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (80205731) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8040 + ... + 15001.

Almost surely, 2^80205721 is an apocalyptic number.

It is an amenable number.

80205721 is a deficient number, since it is larger than the sum of its proper divisors (1386001).

80205721 is an equidigital number, since it uses as much as digits as its factorization.

80205721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23159 (or 23100 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 80205721 is about 8955.7646798026. The cubic root of 80205721 is about 431.2559655830.

Adding to 80205721 its reverse (12750208), we get a palindrome (92955929).

The spelling of 80205721 in words is "eighty million, two hundred five thousand, seven hundred twenty-one".