20509825 has 24 divisors (see below), whose sum is σ = 29248128. Its totient is φ = 13975680.

The previous prime is 20509793. The next prime is 20509831. The reversal of 20509825 is 52890502.

It is a happy number.

It is not a de Polignac number, because 20509825 - 2⁵ = 20509793 is a prime.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 40524 + ... + 41026.

It is an arithmetic number, because the mean of its divisors is an integer number (1218672).

Almost surely, 2^20509825 is an apocalyptic number.

20509825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20509825 is a deficient number, since it is larger than the sum of its proper divisors (8738303).

20509825 is a wasteful number, since it uses less digits than its factorization.

20509825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 753 (or 748 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 31.

The square root of 20509825 is about 4528.7774288432. Note that the first 3 decimals coincide. The cubic root of 20509825 is about 273.7288996337.

The spelling of 20509825 in words is "twenty million, five hundred nine thousand, eight hundred twenty-five".