61321661 has 2 divisors, whose sum is σ = 61321662. Its totient is φ = 61321660.

The previous prime is 61321649. The next prime is 61321717. The reversal of 61321661 is 16612316.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 61136761 + 184900 = 7819^2 + 430^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61321661 is a prime.

It is a super-2 number, since 2×61321661² = 7520692215597842, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 61321661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61321621) 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, 30660830 + 30660831.

It is an arithmetic number, because the mean of its divisors is an integer number (30660831).

Almost surely, 2^61321661 is an apocalyptic number.

It is an amenable number.

61321661 is a deficient number, since it is larger than the sum of its proper divisors (1).

61321661 is an equidigital number, since it uses as much as digits as its factorization.

61321661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 26.

The square root of 61321661 is about 7830.8148362734. The cubic root of 61321661 is about 394.3404278587.

Adding to 61321661 its reverse (16612316), we get a palindrome (77933977).

The spelling of 61321661 in words is "sixty-one million, three hundred twenty-one thousand, six hundred sixty-one".