21361533664 has 24 divisors (see below), whose sum is σ = 42060619440. Its totient is φ = 10679471616.

The previous prime is 21361533649. The next prime is 21361533667. The reversal of 21361533664 is 46633516312.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21361533667) 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, 262392 + ... + 334024.

It is an arithmetic number, because the mean of its divisors is an integer number (1752525810).

Almost surely, 2^21361533664 is an apocalyptic number.

It is an amenable number.

21361533664 is a deficient number, since it is larger than the sum of its proper divisors (20699085776).

21361533664 is an equidigital number, since it uses as much as digits as its factorization.

21361533664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 80962 (or 80954 counting only the distinct ones).

The product of its digits is 233280, while the sum is 40.

It can be divided in two parts, 21361 and 533664, that added together give a square (555025 = 745²).

The spelling of 21361533664 in words is "twenty-one billion, three hundred sixty-one million, five hundred thirty-three thousand, six hundred sixty-four".