10661561501 has 2 divisors, whose sum is σ = 10661561502. Its totient is φ = 10661561500.

The previous prime is 10661561453. The next prime is 10661561587. The reversal of 10661561501 is 10516516601.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10644874276 + 16687225 = 103174^2 + 4085^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-10661561501 is a prime.

It is a super-2 number, since 2×10661561501² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (10661561201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5330780750 + 5330780751.

It is an arithmetic number, because the mean of its divisors is an integer number (5330780751).

Almost surely, 2^10661561501 is an apocalyptic number.

It is an amenable number.

10661561501 is a deficient number, since it is larger than the sum of its proper divisors (1).

10661561501 is an equidigital number, since it uses as much as digits as its factorization.

10661561501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5400, while the sum is 32.

The spelling of 10661561501 in words is "ten billion, six hundred sixty-one million, five hundred sixty-one thousand, five hundred one".