61491521633 has 2 divisors, whose sum is σ = 61491521634. Its totient is φ = 61491521632.

The previous prime is 61491521563. The next prime is 61491521639. The reversal of 61491521633 is 33612519416.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59524776529 + 1966745104 = 243977^2 + 44348^2 .

It is a cyclic number.

It is not a de Polignac number, because 61491521633 - 2¹⁶ = 61491456097 is a prime.

It is not a weakly prime, because it can be changed into another prime (61491521639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30745760816 + 30745760817.

It is an arithmetic number, because the mean of its divisors is an integer number (30745760817).

Almost surely, 2^61491521633 is an apocalyptic number.

It is an amenable number.

61491521633 is a deficient number, since it is larger than the sum of its proper divisors (1).

61491521633 is an equidigital number, since it uses as much as digits as its factorization.

61491521633 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 41.

The spelling of 61491521633 in words is "sixty-one billion, four hundred ninety-one million, five hundred twenty-one thousand, six hundred thirty-three".