21270220645 has 8 divisors (see below), whose sum is σ = 25710574104. Its totient is φ = 16891970304.

The previous prime is 21270220639. The next prime is 21270220649. The reversal of 21270220645 is 54602207212.

It can be written as a sum of positive squares in 4 ways, for example, as 9588718084 + 11681502561 = 97922^2 + 108081^2 .

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 21270220645 - 2¹⁵ = 21270187877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21270220649) 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, 15525024 + ... + 15526393.

It is an arithmetic number, because the mean of its divisors is an integer number (3213821763).

Almost surely, 2^21270220645 is an apocalyptic number.

It is an amenable number.

21270220645 is a deficient number, since it is larger than the sum of its proper divisors (4440353459).

21270220645 is a wasteful number, since it uses less digits than its factorization.

21270220645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31051559.

The product of its (nonzero) digits is 13440, while the sum is 31.

Adding to 21270220645 its reverse (54602207212), we get a palindrome (75872427857).

The spelling of 21270220645 in words is "twenty-one billion, two hundred seventy million, two hundred twenty thousand, six hundred forty-five".