20661225 has 24 divisors (see below), whose sum is σ = 36789312. Its totient is φ = 10171200.

The previous prime is 20661203. The next prime is 20661233. The reversal of 20661225 is 52216602.

It is a de Polignac number, because none of the positive numbers 2^k-20661225 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20661195 and 20661204.

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, 9621 + ... + 11570.

It is an arithmetic number, because the mean of its divisors is an integer number (1532888).

Almost surely, 2^20661225 is an apocalyptic number.

20661225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20661225 is a deficient number, since it is larger than the sum of its proper divisors (16128087).

20661225 is a wasteful number, since it uses less digits than its factorization.

20661225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21217 (or 21212 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 24.

The square root of 20661225 is about 4545.4620227211. The cubic root of 20661225 is about 274.4007889618.

Adding to 20661225 its reverse (52216602), we get a palindrome (72877827).

The spelling of 20661225 in words is "twenty million, six hundred sixty-one thousand, two hundred twenty-five".