21245601563 has 4 divisors (see below), whose sum is σ = 21321208968. Its totient is φ = 21169994160.

The previous prime is 21245601529. The next prime is 21245601569. The reversal of 21245601563 is 36510654212.

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

It is a cyclic number.

It is not a de Polignac number, because 21245601563 - 2¹⁶ = 21245536027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21245601569) 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, 37803281 + ... + 37803842.

It is an arithmetic number, because the mean of its divisors is an integer number (5330302242).

Almost surely, 2^21245601563 is an apocalyptic number.

21245601563 is a deficient number, since it is larger than the sum of its proper divisors (75607405).

21245601563 is an equidigital number, since it uses as much as digits as its factorization.

21245601563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75607404.

The product of its (nonzero) digits is 43200, while the sum is 35.

The spelling of 21245601563 in words is "twenty-one billion, two hundred forty-five million, six hundred one thousand, five hundred sixty-three".