21318625 has 16 divisors (see below), whose sum is σ = 27527760. Its totient is φ = 16464000.

The previous prime is 21318599. The next prime is 21318643. The reversal of 21318625 is 52681312.

21318625 = 48³ + 49³ + ... + 97³.

It can be written as a sum of positive squares in 8 ways, for example, as 3400336 + 17918289 = 1844^2 + 4233^2 .

It is not a de Polignac number, because 21318625 - 2¹³ = 21310433 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21318593 and 21318602.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 685 + ... + 6565.

It is an arithmetic number, because the mean of its divisors is an integer number (1720485).

Almost surely, 2^21318625 is an apocalyptic number.

21318625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21318625 is a deficient number, since it is larger than the sum of its proper divisors (6209135).

21318625 is an equidigital number, since it uses as much as digits as its factorization.

21318625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5925 (or 5915 counting only the distinct ones).

The product of its digits is 2880, while the sum is 28.

The square root of 21318625 is about 4617.2096551922. The cubic root of 21318625 is about 277.2807564067.

Adding to 21318625 its reverse (52681312), we get a palindrome (73999937).

The spelling of 21318625 in words is "twenty-one million, three hundred eighteen thousand, six hundred twenty-five".