61100085721 has 4 divisors (see below), whose sum is σ = 61106875344. Its totient is φ = 61093296100.

The previous prime is 61100085653. The next prime is 61100085731. The reversal of 61100085721 is 12758000116.

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 a de Polignac number, because none of the positive numbers 2^k-61100085721 is a prime.

It is a super-2 number, since 2×61100085721² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61100085731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3381295 + ... + 3399316.

It is an arithmetic number, because the mean of its divisors is an integer number (15276718836).

Almost surely, 2^61100085721 is an apocalyptic number.

It is an amenable number.

61100085721 is a deficient number, since it is larger than the sum of its proper divisors (6789623).

61100085721 is an equidigital number, since it uses as much as digits as its factorization.

61100085721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6789622.

The product of its (nonzero) digits is 3360, while the sum is 31.

Adding to 61100085721 its reverse (12758000116), we get a palindrome (73858085837).

It can be divided in two parts, 6110008 and 5721, that added together give a square (6115729 = 2473²).

The spelling of 61100085721 in words is "sixty-one billion, one hundred million, eighty-five thousand, seven hundred twenty-one".