21285351025 has 9 divisors (see below), whose sum is σ = 26394739851. Its totient is φ = 17027697240.

The previous prime is 21285351019. The next prime is 21285351029. The reversal of 21285351025 is 52015358212.

The square root of 21285351025 is 145895.

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

It can be written as a sum of positive squares in only one way, i.e., 7662726369 + 13622624656 = 87537^2 + 116716^2 .

It is not a de Polignac number, because 21285351025 - 2¹³ = 21285342833 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21285351029) 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 8 ways as a sum of consecutive naturals, for example, 714886 + ... + 744064.

Almost surely, 2^21285351025 is an apocalyptic number.

21285351025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21285351025 is the 145895-th square number.

21285351025 is the 72948-th centered octagonal number.

It is an amenable number.

21285351025 is a deficient number, since it is larger than the sum of its proper divisors (5109388826).

21285351025 is an frugal number, since it uses more digits than its factorization.

21285351025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58368 (or 29184 counting only the distinct ones).

The product of its (nonzero) digits is 24000, while the sum is 34.

The spelling of 21285351025 in words is "twenty-one billion, two hundred eighty-five million, three hundred fifty-one thousand, twenty-five".