21816767025 has 81 divisors (see below), whose sum is σ = 40181599809. Its totient is φ = 11315384640.

The previous prime is 21816767023. The next prime is 21816767057. The reversal of 21816767025 is 52076761812.

The square root of 21816767025 is 147705.

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 2977557489 + 18839209536 = 54567^2 + 137256^2 .

It is not a de Polignac number, because 21816767025 - 2¹ = 21816767023 is a prime.

It is a super-3 number, since 3×21816767025³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21816767023) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 95269611 + ... + 95269839.

Almost surely, 2^21816767025 is an apocalyptic number.

21816767025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21816767025 is the 147705-th square number.

21816767025 is the 73853-rd centered octagonal number.

It is an amenable number.

21816767025 is a deficient number, since it is larger than the sum of its proper divisors (18364832784).

21816767025 is an equidigital number, since it uses as much as digits as its factorization.

21816767025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 560 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 282240, while the sum is 45.

The spelling of 21816767025 in words is "twenty-one billion, eight hundred sixteen million, seven hundred sixty-seven thousand, twenty-five".