21563454025 has 27 divisors (see below), whose sum is σ = 27415113159. Its totient is φ = 16824912720.

The previous prime is 21563454001. The next prime is 21563454043. The reversal of 21563454025 is 52045436512.

The square root of 21563454025 is 146845.

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., 7762843449 + 13800610576 = 88107^2 + 117476^2 .

It is not a de Polignac number, because 21563454025 - 2¹¹ = 21563451977 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 31571334 + ... + 31572016.

Almost surely, 2^21563454025 is an apocalyptic number.

21563454025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21563454025 is the 146845-th square number.

21563454025 is the 73423-rd centered octagonal number.

It is an amenable number.

21563454025 is a deficient number, since it is larger than the sum of its proper divisors (5851659134).

21563454025 is an frugal number, since it uses more digits than its factorization.

21563454025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1462 (or 731 counting only the distinct ones).

The product of its (nonzero) digits is 144000, while the sum is 37.

The spelling of 21563454025 in words is "twenty-one billion, five hundred sixty-three million, four hundred fifty-four thousand, twenty-five".