21973615225 has 27 divisors (see below), whose sum is σ = 28505568973. Its totient is φ = 16801547840.

The previous prime is 21973615187. The next prime is 21973615267. The reversal of 21973615225 is 52251637912.

It is a happy number.

The square root of 21973615225 is 148235.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 817330921 + 21156284304 = 28589^2 + 145452^2 .

It is not a de Polignac number, because 21973615225 - 2⁹ = 21973614713 is a prime.

It is a Duffinian number.

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 26 ways as a sum of consecutive naturals, for example, 17046381 + ... + 17047669.

Almost surely, 2^21973615225 is an apocalyptic number.

21973615225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21973615225 is the 148235-th square number.

21973615225 is the 74118-th centered octagonal number.

It is an amenable number.

21973615225 is a deficient number, since it is larger than the sum of its proper divisors (6531953748).

21973615225 is an frugal number, since it uses more digits than its factorization.

21973615225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2634 (or 1317 counting only the distinct ones).

The product of its digits is 226800, while the sum is 43.

The spelling of 21973615225 in words is "twenty-one billion, nine hundred seventy-three million, six hundred fifteen thousand, two hundred twenty-five".