21405144554125 has 64 divisors (see below), whose sum is σ = 28011539791872. Its totient is φ = 16299525000000.

The previous prime is 21405144554119. The next prime is 21405144554173. The reversal of 21405144554125 is 52145544150412.

It is not a de Polignac number, because 21405144554125 - 2³ = 21405144554117 is a prime.

It is a Duffinian number.

It is a congruent number.

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 63 ways as a sum of consecutive naturals, for example, 830577490 + ... + 830603260.

It is an arithmetic number, because the mean of its divisors is an integer number (437680309248).

Almost surely, 2^{21405144554125} is an apocalyptic number.

21405144554125 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21405144554125 is a deficient number, since it is larger than the sum of its proper divisors (6606395237747).

21405144554125 is a wasteful number, since it uses less digits than its factorization.

21405144554125 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27211 (or 27201 counting only the distinct ones).

The product of its (nonzero) digits is 640000, while the sum is 43.

The spelling of 21405144554125 in words is "twenty-one trillion, four hundred five billion, one hundred forty-four million, five hundred fifty-four thousand, one hundred twenty-five".