21305670681 has 8 divisors (see below), whose sum is σ = 28512386944. Its totient is φ = 14151367440.

The previous prime is 21305670667. The next prime is 21305670697. The reversal of 21305670681 is 18607650312.

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

It is not a de Polignac number, because 21305670681 - 2¹⁰ = 21305669657 is a prime.

It is a super-2 number, since 2×21305670681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21305670601) 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, 13102306 + ... + 13103931.

It is an arithmetic number, because the mean of its divisors is an integer number (3564048368).

Almost surely, 2^21305670681 is an apocalyptic number.

It is an amenable number.

21305670681 is a deficient number, since it is larger than the sum of its proper divisors (7206716263).

21305670681 is a wasteful number, since it uses less digits than its factorization.

21305670681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26206511.

The product of its (nonzero) digits is 60480, while the sum is 39.

The spelling of 21305670681 in words is "twenty-one billion, three hundred five million, six hundred seventy thousand, six hundred eighty-one".