21561650007 has 16 divisors (see below), whose sum is σ = 29681774592. Its totient is φ = 13908152160.

The previous prime is 21561649997. The next prime is 21561650009. The reversal of 21561650007 is 70005616512.

It is not a de Polignac number, because 21561650007 - 2⁸ = 21561649751 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21561650007.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21561650009) 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 15 ways as a sum of consecutive naturals, for example, 566253 + ... + 603129.

It is an arithmetic number, because the mean of its divisors is an integer number (1855110912).

Almost surely, 2^21561650007 is an apocalyptic number.

21561650007 is a deficient number, since it is larger than the sum of its proper divisors (8120124585).

21561650007 is a wasteful number, since it uses less digits than its factorization.

21561650007 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43198.

The product of its (nonzero) digits is 12600, while the sum is 33.

The spelling of 21561650007 in words is "twenty-one billion, five hundred sixty-one million, six hundred fifty thousand, seven".