61155581 has 4 divisors (see below), whose sum is σ = 61172832. Its totient is φ = 61138332.

The previous prime is 61155571. The next prime is 61155593. The reversal of 61155581 is 18555116.

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 not a de Polignac number, because 61155581 - 2⁶ = 61155517 is a prime.

It is a super-2 number, since 2×61155581² = 7480010174895122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61155541) 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, 1145 + ... + 11118.

It is an arithmetic number, because the mean of its divisors is an integer number (15293208).

Almost surely, 2^61155581 is an apocalyptic number.

It is an amenable number.

61155581 is a deficient number, since it is larger than the sum of its proper divisors (17251).

61155581 is a wasteful number, since it uses less digits than its factorization.

61155581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17250.

The product of its digits is 6000, while the sum is 32.

The square root of 61155581 is about 7820.2033861019. The cubic root of 61155581 is about 393.9841031318.

The spelling of 61155581 in words is "sixty-one million, one hundred fifty-five thousand, five hundred eighty-one".