21145543025 has 12 divisors (see below), whose sum is σ = 26222589132. Its totient is φ = 16915069440.

The previous prime is 21145542961. The next prime is 21145543087. The reversal of 21145543025 is 52034554112.

It can be written as a sum of positive squares in 6 ways, for example, as 1860110641 + 19285432384 = 43129^2 + 138872^2 .

It is not a de Polignac number, because 21145543025 - 2⁶ = 21145542961 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21145542982 and 21145543000.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 380837 + ... + 432813.

It is an arithmetic number, because the mean of its divisors is an integer number (2185215761).

Almost surely, 2^21145543025 is an apocalyptic number.

21145543025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21145543025 is a deficient number, since it is larger than the sum of its proper divisors (5077046107).

21145543025 is a wasteful number, since it uses less digits than its factorization.

21145543025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68260 (or 68255 counting only the distinct ones).

The product of its (nonzero) digits is 24000, while the sum is 32.

The spelling of 21145543025 in words is "twenty-one billion, one hundred forty-five million, five hundred forty-three thousand, twenty-five".