21051023905 has 16 divisors (see below), whose sum is σ = 25615989504. Its totient is φ = 16605596160.

The previous prime is 21051023893. The next prime is 21051023921. The reversal of 21051023905 is 50932015012.

It is not a de Polignac number, because 21051023905 - 2¹⁷ = 21050892833 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 51354 + ... + 211516.

It is an arithmetic number, because the mean of its divisors is an integer number (1600999344).

Almost surely, 2^21051023905 is an apocalyptic number.

It is an amenable number.

21051023905 is a deficient number, since it is larger than the sum of its proper divisors (4564965599).

21051023905 is a wasteful number, since it uses less digits than its factorization.

21051023905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160536.

The product of its (nonzero) digits is 2700, while the sum is 28.

Adding to 21051023905 its reverse (50932015012), we get a palindrome (71983038917).

The spelling of 21051023905 in words is "twenty-one billion, fifty-one million, twenty-three thousand, nine hundred five".