61656561 has 12 divisors (see below), whose sum is σ = 89942580. Its totient is φ = 40696800.

The previous prime is 61656559. The next prime is 61656563. The reversal of 61656561 is 16565616.

It is an interprime number because it is at equal distance from previous prime (61656559) and next prime (61656563).

It can be written as a sum of positive squares in 2 ways, for example, as 53012961 + 8643600 = 7281^2 + 2940^2 .

It is not a de Polignac number, because 61656561 - 2¹ = 61656559 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (61656563) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33006 + ... + 34823.

It is an arithmetic number, because the mean of its divisors is an integer number (7495215).

Almost surely, 2^61656561 is an apocalyptic number.

It is an amenable number.

61656561 is a deficient number, since it is larger than the sum of its proper divisors (28286019).

61656561 is a wasteful number, since it uses less digits than its factorization.

61656561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67936 (or 67933 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 61656561 is about 7852.1691907396. The cubic root of 61656561 is about 395.0570040041.

The spelling of 61656561 in words is "sixty-one million, six hundred fifty-six thousand, five hundred sixty-one".