21424263661 has 8 divisors (see below), whose sum is σ = 22005297944. Its totient is φ = 20843334720.

The previous prime is 21424263569. The next prime is 21424263683. The reversal of 21424263661 is 16636242412.

It can be written as a sum of positive squares in 4 ways, for example, as 10993522500 + 10430741161 = 104850^2 + 102131^2 .

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 21424263661 - 2¹⁹ = 21423739373 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21424263661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21424263361) 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, 560971 + ... + 597943.

It is an arithmetic number, because the mean of its divisors is an integer number (2750662243).

Almost surely, 2^21424263661 is an apocalyptic number.

It is an amenable number.

21424263661 is a deficient number, since it is larger than the sum of its proper divisors (581034283).

21424263661 is a wasteful number, since it uses less digits than its factorization.

21424263661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52671.

The product of its digits is 82944, while the sum is 37.

The spelling of 21424263661 in words is "twenty-one billion, four hundred twenty-four million, two hundred sixty-three thousand, six hundred sixty-one".