20728925 has 24 divisors (see below), whose sum is σ = 30331392. Its totient is φ = 13752000.

The previous prime is 20728921. The next prime is 20728949. The reversal of 20728925 is 52982702.

It is not a de Polignac number, because 20728925 - 2² = 20728921 is a prime.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (35).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20728921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3515 + ... + 7335.

It is an arithmetic number, because the mean of its divisors is an integer number (1263808).

Almost surely, 2^20728925 is an apocalyptic number.

20728925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20728925 is a deficient number, since it is larger than the sum of its proper divisors (9602467).

20728925 is a wasteful number, since it uses less digits than its factorization.

20728925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3869 (or 3864 counting only the distinct ones).

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 20728925 is about 4552.9029201159. The cubic root of 20728925 is about 274.7001690827.

The spelling of 20728925 in words is "twenty million, seven hundred twenty-eight thousand, nine hundred twenty-five".