21318240340225 has 24 divisors (see below), whose sum is σ = 26615448343800. Its totient is φ = 16937956945920.

The previous prime is 21318240340157. The next prime is 21318240340279. The reversal of 21318240340225 is 52204304281312.

It is a Cunningham number, because it is equal to 4617168²+1.

It can be written as a sum of positive squares in 12 ways, for example, as 20102875206129 + 1215365134096 = 4483623^2 + 1102436^2 .

It is not a de Polignac number, because 21318240340225 - 2³¹ = 21316092856577 is a prime.

It is a super-3 number, since 3×21318240340225³ (a number of 41 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28963467 + ... + 29690383.

It is an arithmetic number, because the mean of its divisors is an integer number (1108977014325).

Almost surely, 2^{21318240340225} is an apocalyptic number.

21318240340225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21318240340225 is a deficient number, since it is larger than the sum of its proper divisors (5297208003575).

21318240340225 is a wasteful number, since it uses less digits than its factorization.

21318240340225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 734949 (or 734944 counting only the distinct ones).

The product of its (nonzero) digits is 92160, while the sum is 37.

The spelling of 21318240340225 in words is "twenty-one trillion, three hundred eighteen billion, two hundred forty million, three hundred forty thousand, two hundred twenty-five".