21660253667 has 8 divisors (see below), whose sum is σ = 23822734656. Its totient is φ = 19568673792.

The previous prime is 21660253663. The next prime is 21660253781. The reversal of 21660253667 is 76635206612.

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 21660253667 - 2² = 21660253663 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21660253661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17724638 + ... + 17725859.

It is an arithmetic number, because the mean of its divisors is an integer number (2977841832).

Almost surely, 2^21660253667 is an apocalyptic number.

21660253667 is a deficient number, since it is larger than the sum of its proper divisors (2162480989).

21660253667 is a wasteful number, since it uses less digits than its factorization.

21660253667 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35450557.

The product of its (nonzero) digits is 544320, while the sum is 44.

The spelling of 21660253667 in words is "twenty-one billion, six hundred sixty million, two hundred fifty-three thousand, six hundred sixty-seven".