21506201326044 has 18 divisors (see below), whose sum is σ = 54362897796480. Its totient is φ = 7168733775336.

The previous prime is 21506201326013. The next prime is 21506201326073. The reversal of 21506201326044 is 44062310260512.

21506201326044 is a `hidden beast` number, since 2 + 1 + 5 + 0 + 620 + 1 + 3 + 26 + 0 + 4 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 597394481279 = 21506201326044 / (2 + 1 + 5 + 0 + 6 + 2 + 0 + 1 + 3 + 2 + 6 + 0 + 4 + 4).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 298697240604 + ... + 298697240675.

Almost surely, 2^{21506201326044} is an apocalyptic number.

It is an amenable number.

21506201326044 is an abundant number, since it is smaller than the sum of its proper divisors (32856696470436).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21506201326044 is a wasteful number, since it uses less digits than its factorization.

21506201326044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 597394481289 (or 597394481284 counting only the distinct ones).

The product of its (nonzero) digits is 69120, while the sum is 36.

Adding to 21506201326044 its reverse (44062310260512), we get a palindrome (65568511586556).

The spelling of 21506201326044 in words is "twenty-one trillion, five hundred six billion, two hundred one million, three hundred twenty-six thousand, forty-four".