61561631 has 2 divisors, whose sum is σ = 61561632. Its totient is φ = 61561630.

The previous prime is 61561613. The next prime is 61561649. The reversal of 61561631 is 13616516.

Together with previous prime (61561613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (61561613) and next prime (61561649).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61561631 is a prime.

It is a super-5 number, since 5×61561631⁵ (a number of 40 digits) contains 55555 as substring. Note that it is a super-d number also for d = 2.

It is a junction number, because it is equal to n+sod(n) for n = 61561594 and 61561603.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61561601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30780815 + 30780816.

It is an arithmetic number, because the mean of its divisors is an integer number (30780816).

Almost surely, 2^61561631 is an apocalyptic number.

61561631 is a deficient number, since it is larger than the sum of its proper divisors (1).

61561631 is an equidigital number, since it uses as much as digits as its factorization.

61561631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3240, while the sum is 29.

The square root of 61561631 is about 7846.1220357575. The cubic root of 61561631 is about 394.8541490043.

The spelling of 61561631 in words is "sixty-one million, five hundred sixty-one thousand, six hundred thirty-one".