209759420025 has 81 divisors (see below), whose sum is σ = 396763863951. Its totient is φ = 105917755680.

The previous prime is 209759419973. The next prime is 209759420027. The reversal of 209759420025 is 520024957902.

The square root of 209759420025 is 457995.

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., 75513391209 + 134246028816 = 274797^2 + 366396^2 .

It is not a de Polignac number, because 209759420025 - 2⁷ = 209759419897 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (209759420027) 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, 130527772 + ... + 130529378.

Almost surely, 2^209759420025 is an apocalyptic number.

209759420025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

209759420025 is the 457995-th square number.

209759420025 is the 228998-th centered octagonal number.

It is an amenable number.

209759420025 is a deficient number, since it is larger than the sum of its proper divisors (187004443926).

209759420025 is an equidigital number, since it uses as much as digits as its factorization.

209759420025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3268 (or 1634 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 45.

The spelling of 209759420025 in words is "two hundred nine billion, seven hundred fifty-nine million, four hundred twenty thousand, twenty-five".