21504340053 has 16 divisors (see below), whose sum is σ = 36409464960. Its totient is φ = 12288194208.

The previous prime is 21504340051. The next prime is 21504340057. The reversal of 21504340053 is 35004340512.

21504340053 is a `hidden beast` number, since 215 + 0 + 43 + 400 + 5 + 3 = 666.

It is not a de Polignac number, because 21504340053 - 2¹ = 21504340051 is a prime.

It is a super-2 number, since 2×21504340053² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 21504339999 and 21504340026.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21504340051) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 56889600 + ... + 56889977.

It is an arithmetic number, because the mean of its divisors is an integer number (2275591560).

Almost surely, 2^21504340053 is an apocalyptic number.

It is an amenable number.

21504340053 is a deficient number, since it is larger than the sum of its proper divisors (14905124907).

21504340053 is a wasteful number, since it uses less digits than its factorization.

21504340053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 113779593 (or 113779587 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 27.

Adding to 21504340053 its reverse (35004340512), we get a palindrome (56508680565).

The spelling of 21504340053 in words is "twenty-one billion, five hundred four million, three hundred forty thousand, fifty-three".