21072877225 has 9 divisors (see below), whose sum is σ = 26131267813. Its totient is φ = 16857721120.

The previous prime is 21072877169. The next prime is 21072877261. The reversal of 21072877225 is 52277827012.

The square root of 21072877225 is 145165.

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 1772999449 + 19299877776 = 42107^2 + 138924^2 .

It is not a de Polignac number, because 21072877225 - 2¹³ = 21072869033 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 711309 + ... + 740341.

Almost surely, 2^21072877225 is an apocalyptic number.

21072877225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21072877225 is the 145165-th square number.

21072877225 is the 72583-rd centered octagonal number.

It is an amenable number.

21072877225 is a deficient number, since it is larger than the sum of its proper divisors (5058390588).

21072877225 is an frugal number, since it uses more digits than its factorization.

21072877225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58076 (or 29038 counting only the distinct ones).

The product of its (nonzero) digits is 219520, while the sum is 43.

The spelling of 21072877225 in words is "twenty-one billion, seventy-two million, eight hundred seventy-seven thousand, two hundred twenty-five".