21015250305 has 128 divisors (see below), whose sum is σ = 40783454208. Its totient is φ = 9033818112.

The previous prime is 21015250301. The next prime is 21015250313. The reversal of 21015250305 is 50305251012.

It is a happy number.

It is not a de Polignac number, because 21015250305 - 2² = 21015250301 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21015250301) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 66294007 + ... + 66294323.

It is an arithmetic number, because the mean of its divisors is an integer number (318620736).

Almost surely, 2^21015250305 is an apocalyptic number.

It is an amenable number.

21015250305 is a deficient number, since it is larger than the sum of its proper divisors (19768203903).

21015250305 is a wasteful number, since it uses less digits than its factorization.

21015250305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 735.

The product of its (nonzero) digits is 1500, while the sum is 24.

The spelling of 21015250305 in words is "twenty-one billion, fifteen million, two hundred fifty thousand, three hundred five".