21661730287 has 8 divisors (see below), whose sum is σ = 21786816240. Its totient is φ = 21536689920.

The previous prime is 21661730281. The next prime is 21661730323. The reversal of 21661730287 is 78203716612.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21661730287 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661730281) 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 in 7 ways as a sum of consecutive naturals, for example, 1549087 + ... + 1563007.

It is an arithmetic number, because the mean of its divisors is an integer number (2723352030).

Almost surely, 2^21661730287 is an apocalyptic number.

21661730287 is a deficient number, since it is larger than the sum of its proper divisors (125085953).

21661730287 is a wasteful number, since it uses less digits than its factorization.

21661730287 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22793.

The product of its (nonzero) digits is 169344, while the sum is 43.

The spelling of 21661730287 in words is "twenty-one billion, six hundred sixty-one million, seven hundred thirty thousand, two hundred eighty-seven".