61115721 has 8 divisors (see below), whose sum is σ = 81633120. Its totient is φ = 40671072.

The previous prime is 61115713. The next prime is 61115737. The reversal of 61115721 is 12751116.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 61115721 - 2³ = 61115713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 61115691 and 61115700.

It is not an unprimeable number, because it can be changed into a prime (61115521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16195 + ... + 19608.

It is an arithmetic number, because the mean of its divisors is an integer number (10204140).

Almost surely, 2^61115721 is an apocalyptic number.

It is an amenable number.

61115721 is a deficient number, since it is larger than the sum of its proper divisors (20517399).

61115721 is a wasteful number, since it uses less digits than its factorization.

61115721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36375.

The product of its digits is 420, while the sum is 24.

The square root of 61115721 is about 7817.6544436295. The cubic root of 61115721 is about 393.8984875089.

Adding to 61115721 its reverse (12751116), we get a palindrome (73866837).

The spelling of 61115721 in words is "sixty-one million, one hundred fifteen thousand, seven hundred twenty-one".