21155154520425 has 48 divisors (see below), whose sum is σ = 36503211644928. Its totient is φ = 10790429108800.

The previous prime is 21155154520411. The next prime is 21155154520441. The reversal of 21155154520425 is 52402545155112.

It is not a de Polignac number, because 21155154520425 - 2⁹ = 21155154519913 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9575824 + ... + 11576126.

It is an arithmetic number, because the mean of its divisors is an integer number (760483575936).

Almost surely, 2^{21155154520425} is an apocalyptic number.

21155154520425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21155154520425 is a deficient number, since it is larger than the sum of its proper divisors (15348057124503).

21155154520425 is a wasteful number, since it uses less digits than its factorization.

21155154520425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2006470 (or 2006465 counting only the distinct ones).

The product of its (nonzero) digits is 400000, while the sum is 42.

Adding to 21155154520425 its reverse (52402545155112), we get a palindrome (73557699675537).

The spelling of 21155154520425 in words is "twenty-one trillion, one hundred fifty-five billion, one hundred fifty-four million, five hundred twenty thousand, four hundred twenty-five".