21346654561 has 4 divisors (see below), whose sum is σ = 21843088432. Its totient is φ = 20850220692.

The previous prime is 21346654559. The next prime is 21346654661. The reversal of 21346654561 is 16545664312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21346654561 - 2¹ = 21346654559 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 496433827 = 21346654561 / (2 + 1 + 3 + 4 + 6 + 6 + 5 + 4 + 5 + 6 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21346654501) 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, 248216871 + ... + 248216956.

It is an arithmetic number, because the mean of its divisors is an integer number (5460772108).

Almost surely, 2^21346654561 is an apocalyptic number.

It is an amenable number.

21346654561 is a deficient number, since it is larger than the sum of its proper divisors (496433871).

21346654561 is an equidigital number, since it uses as much as digits as its factorization.

21346654561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 496433870.

The product of its digits is 518400, while the sum is 43.

The spelling of 21346654561 in words is "twenty-one billion, three hundred forty-six million, six hundred fifty-four thousand, five hundred sixty-one".