61810561 has 4 divisors (see below), whose sum is σ = 62976852. Its totient is φ = 60644272.

The previous prime is 61810537. The next prime is 61810579. The reversal of 61810561 is 16501816.

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 21678336 + 40132225 = 4656^2 + 6335^2 .

It is a cyclic number.

It is not a de Polignac number, because 61810561 - 2¹⁷ = 61679489 is a prime.

It is a super-2 number, since 2×61810561² = 7641090902269442, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61810501) 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, 583066 + ... + 583171.

It is an arithmetic number, because the mean of its divisors is an integer number (15744213).

Almost surely, 2^61810561 is an apocalyptic number.

It is an amenable number.

61810561 is a deficient number, since it is larger than the sum of its proper divisors (1166291).

61810561 is a wasteful number, since it uses less digits than its factorization.

61810561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1166290.

The product of its (nonzero) digits is 1440, while the sum is 28.

The square root of 61810561 is about 7861.9692825653. The cubic root of 61810561 is about 395.3856427049.

The spelling of 61810561 in words is "sixty-one million, eight hundred ten thousand, five hundred sixty-one".