21245515225 has 24 divisors (see below), whose sum is σ = 28809807840. Its totient is φ = 15413424000.

The previous prime is 21245515223. The next prime is 21245515271. The reversal of 21245515225 is 52251554212.

It is not a de Polignac number, because 21245515225 - 2¹ = 21245515223 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21245515223) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 18030 + ... + 206920.

It is an arithmetic number, because the mean of its divisors is an integer number (1200408660).

Almost surely, 2^21245515225 is an apocalyptic number.

21245515225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21245515225 is a deficient number, since it is larger than the sum of its proper divisors (7564292615).

21245515225 is a wasteful number, since it uses less digits than its factorization.

21245515225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189321 (or 189316 counting only the distinct ones).

The product of its digits is 40000, while the sum is 34.

The spelling of 21245515225 in words is "twenty-one billion, two hundred forty-five million, five hundred fifteen thousand, two hundred twenty-five".