61158721 has 4 divisors (see below), whose sum is σ = 65863252. Its totient is φ = 56454192.

The previous prime is 61158697. The next prime is 61158731. The reversal of 61158721 is 12785116.

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 37344321 + 23814400 = 6111^2 + 4880^2 .

It is a cyclic number.

It is not a de Polignac number, because 61158721 - 2²⁵ = 27604289 is a prime.

It is not an unprimeable number, because it can be changed into a prime (61158731) 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, 2352246 + ... + 2352271.

It is an arithmetic number, because the mean of its divisors is an integer number (16465813).

Almost surely, 2^61158721 is an apocalyptic number.

It is an amenable number.

61158721 is a deficient number, since it is larger than the sum of its proper divisors (4704531).

61158721 is a wasteful number, since it uses less digits than its factorization.

61158721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4704530.

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

The square root of 61158721 is about 7820.4041455669. The cubic root of 61158721 is about 393.9908459828.

The spelling of 61158721 in words is "sixty-one million, one hundred fifty-eight thousand, seven hundred twenty-one".