21125242105 has 8 divisors (see below), whose sum is σ = 27654862464. Its totient is φ = 15363812400.

The previous prime is 21125242081. The next prime is 21125242121. The reversal of 21125242105 is 50124252112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21125242105 - 2⁹ = 21125241593 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21125242105.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 192047601 + ... + 192047710.

It is an arithmetic number, because the mean of its divisors is an integer number (3456857808).

Almost surely, 2^21125242105 is an apocalyptic number.

It is an amenable number.

21125242105 is a deficient number, since it is larger than the sum of its proper divisors (6529620359).

21125242105 is a wasteful number, since it uses less digits than its factorization.

21125242105 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 384095327.

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 21125242105 its reverse (50124252112), we get a palindrome (71249494217).

The spelling of 21125242105 in words is "twenty-one billion, one hundred twenty-five million, two hundred forty-two thousand, one hundred five".