10561991 has 16 divisors (see below), whose sum is σ = 12165120. Its totient is φ = 9076320.

The previous prime is 10561987. The next prime is 10562009. The reversal of 10561991 is 19916501.

It is a happy number.

It is not a de Polignac number, because 10561991 - 2² = 10561987 is a prime.

It is a super-2 number, since 2×10561991² = 223111307768162, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (10561921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27386 + ... + 27768.

It is an arithmetic number, because the mean of its divisors is an integer number (760320).

Almost surely, 2^10561991 is an apocalyptic number.

10561991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

10561991 is a deficient number, since it is larger than the sum of its proper divisors (1603129).

10561991 is a wasteful number, since it uses less digits than its factorization.

10561991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 526.

The product of its (nonzero) digits is 2430, while the sum is 32.

The square root of 10561991 is about 3249.9216913643. The cubic root of 10561991 is about 219.4060494251.

The spelling of 10561991 in words is "ten million, five hundred sixty-one thousand, nine hundred ninety-one".