21346305661 has 4 divisors (see below), whose sum is σ = 21557655324. Its totient is φ = 21134956000.

The previous prime is 21346305653. The next prime is 21346305691. The reversal of 21346305661 is 16650364312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 16334373636 + 5011932025 = 127806^2 + 70795^2 .

It is a cyclic number.

It is not a de Polignac number, because 21346305661 - 2³ = 21346305653 is a prime.

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 21346305661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21346305691) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105674680 + ... + 105674881.

It is an arithmetic number, because the mean of its divisors is an integer number (5389413831).

Almost surely, 2^21346305661 is an apocalyptic number.

It is an amenable number.

21346305661 is a deficient number, since it is larger than the sum of its proper divisors (211349663).

21346305661 is a wasteful number, since it uses less digits than its factorization.

21346305661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 211349662.

The product of its (nonzero) digits is 77760, while the sum is 37.

Adding to 21346305661 its reverse (16650364312), we get a palindrome (37996669973).

The spelling of 21346305661 in words is "twenty-one billion, three hundred forty-six million, three hundred five thousand, six hundred sixty-one".