21784284025 has 27 divisors (see below), whose sum is σ = 31430171469. Its totient is φ = 14934252480.

The previous prime is 21784284023. The next prime is 21784284059. The reversal of 21784284025 is 52048248712.

The square root of 21784284025 is 147595.

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 1940490601 + 19843793424 = 44051^2 + 140868^2 .

It is not a de Polignac number, because 21784284025 - 2¹ = 21784284023 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21784284023) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 5163717 + ... + 5167933.

Almost surely, 2^21784284025 is an apocalyptic number.

21784284025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21784284025 is the 147595-th square number.

21784284025 is the 73798-th centered octagonal number.

It is an amenable number.

21784284025 is a deficient number, since it is larger than the sum of its proper divisors (9645887444).

21784284025 is an frugal number, since it uses more digits than its factorization.

21784284025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8458 (or 4229 counting only the distinct ones).

The product of its (nonzero) digits is 286720, while the sum is 43.

It can be divided in two parts, 21784 and 284025, that added together give a square (305809 = 553²).

The spelling of 21784284025 in words is "twenty-one billion, seven hundred eighty-four million, two hundred eighty-four thousand, twenty-five".