21525121455 has 16 divisors (see below), whose sum is σ = 36466088544. Its totient is φ = 10804766720.

The previous prime is 21525121441. The next prime is 21525121459. The reversal of 21525121455 is 55412152512.

It is not a de Polignac number, because 21525121455 - 2¹⁴ = 21525105071 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21525121459) 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, 42205866 + ... + 42206375.

It is an arithmetic number, because the mean of its divisors is an integer number (2279130534).

Almost surely, 2^21525121455 is an apocalyptic number.

21525121455 is a deficient number, since it is larger than the sum of its proper divisors (14940967089).

21525121455 is a wasteful number, since it uses less digits than its factorization.

21525121455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84412266.

The product of its digits is 20000, while the sum is 33.

Adding to 21525121455 its reverse (55412152512), we get a palindrome (76937273967).

The spelling of 21525121455 in words is "twenty-one billion, five hundred twenty-five million, one hundred twenty-one thousand, four hundred fifty-five".