21010099561 has 8 divisors (see below), whose sum is σ = 22925346048. Its totient is φ = 19095726000.

The previous prime is 21010099543. The next prime is 21010099589. The reversal of 21010099561 is 16599001012.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21010099561 - 2²¹ = 21008002409 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21010099541) 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 in 7 ways as a sum of consecutive naturals, for example, 167385 + ... + 264646.

It is an arithmetic number, because the mean of its divisors is an integer number (2865668256).

Almost surely, 2^21010099561 is an apocalyptic number.

It is an amenable number.

21010099561 is a deficient number, since it is larger than the sum of its proper divisors (1915246487).

21010099561 is a wasteful number, since it uses less digits than its factorization.

21010099561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 436463.

The product of its (nonzero) digits is 4860, while the sum is 34.

The spelling of 21010099561 in words is "twenty-one billion, ten million, ninety-nine thousand, five hundred sixty-one".