21240625 has 24 divisors (see below), whose sum is σ = 30373056. Its totient is φ = 14550000.

The previous prime is 21240587. The next prime is 21240631. The reversal of 21240625 is 52604212.

It is a de Polignac number, because none of the positive numbers 2^k-21240625 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21240596 and 21240605.

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, 21390 + ... + 22360.

It is an arithmetic number, because the mean of its divisors is an integer number (1265544).

Almost surely, 2^21240625 is an apocalyptic number.

21240625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21240625 is a deficient number, since it is larger than the sum of its proper divisors (9132431).

21240625 is an frugal number, since it uses more digits than its factorization.

21240625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1003 (or 983 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21240625 is about 4608.7552549468. The cubic root of 21240625 is about 276.9421740648.

Adding to 21240625 its reverse (52604212), we get a palindrome (73844837).

The spelling of 21240625 in words is "twenty-one million, two hundred forty thousand, six hundred twenty-five".