61491521563 has 2 divisors, whose sum is σ = 61491521564. Its totient is φ = 61491521562.

The previous prime is 61491521537. The next prime is 61491521633. The reversal of 61491521563 is 36512519416.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-61491521563 is a prime.

It is not a weakly prime, because it can be changed into another prime (61491521263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30745760781 + 30745760782.

It is an arithmetic number, because the mean of its divisors is an integer number (30745760782).

Almost surely, 2^61491521563 is an apocalyptic number.

61491521563 is a deficient number, since it is larger than the sum of its proper divisors (1).

61491521563 is an equidigital number, since it uses as much as digits as its factorization.

61491521563 is an evil number, because the sum of its binary digits is even.

The product of its digits is 194400, while the sum is 43.

The spelling of 61491521563 in words is "sixty-one billion, four hundred ninety-one million, five hundred twenty-one thousand, five hundred sixty-three".