61755721 has 4 divisors (see below), whose sum is σ = 61950852. Its totient is φ = 61560592.

The previous prime is 61755677. The next prime is 61755739. The reversal of 61755721 is 12755716.

It is a happy number.

61755721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29550096 + 32205625 = 5436^2 + 5675^2 .

It is a cyclic number.

It is not a de Polignac number, because 61755721 - 2¹³ = 61747529 is a prime.

It is a super-3 number, since 3×61755721³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61755121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97090 + ... + 97723.

It is an arithmetic number, because the mean of its divisors is an integer number (15487713).

Almost surely, 2^61755721 is an apocalyptic number.

It is an amenable number.

61755721 is a deficient number, since it is larger than the sum of its proper divisors (195131).

61755721 is a wasteful number, since it uses less digits than its factorization.

61755721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 195130.

The product of its digits is 14700, while the sum is 34.

The square root of 61755721 is about 7858.4808328328. The cubic root of 61755721 is about 395.2686758305.

The spelling of 61755721 in words is "sixty-one million, seven hundred fifty-five thousand, seven hundred twenty-one".