21461666213 has 8 divisors (see below), whose sum is σ = 23372256600. Its totient is φ = 19588174848.

The previous prime is 21461666209. The next prime is 21461666251. The reversal of 21461666213 is 31266616412.

It can be written as a sum of positive squares in 4 ways, for example, as 3169915204 + 18291751009 = 56302^2 + 135247^2 .

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 21461666213 - 2² = 21461666209 is a prime.

It is a super-2 number, since 2×21461666213² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21461666293) 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, 9273548 + ... + 9275861.

It is an arithmetic number, because the mean of its divisors is an integer number (2921532075).

Almost surely, 2^21461666213 is an apocalyptic number.

It is an amenable number.

21461666213 is a deficient number, since it is larger than the sum of its proper divisors (1910590387).

21461666213 is a wasteful number, since it uses less digits than its factorization.

21461666213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18549511.

The product of its digits is 62208, while the sum is 38.

The spelling of 21461666213 in words is "twenty-one billion, four hundred sixty-one million, six hundred sixty-six thousand, two hundred thirteen".