61111721721 has 16 divisors (see below), whose sum is σ = 84715632000. Its totient is φ = 39138599808.

The previous prime is 61111721719. The next prime is 61111721767. The reversal of 61111721721 is 12712711116.

It is not a de Polignac number, because 61111721721 - 2¹ = 61111721719 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61111721711) 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, 1747596 + ... + 1782221.

It is an arithmetic number, because the mean of its divisors is an integer number (5294727000).

Almost surely, 2^61111721721 is an apocalyptic number.

It is an amenable number.

61111721721 is a deficient number, since it is larger than the sum of its proper divisors (23603910279).

61111721721 is a wasteful number, since it uses less digits than its factorization.

61111721721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3530048.

The product of its digits is 1176, while the sum is 30.

The spelling of 61111721721 in words is "sixty-one billion, one hundred eleven million, seven hundred twenty-one thousand, seven hundred twenty-one".