20781725 has 24 divisors (see below), whose sum is σ = 27572640. Its totient is φ = 15491520.

The previous prime is 20781703. The next prime is 20781731. The reversal of 20781725 is 52718702.

It is not a de Polignac number, because 20781725 - 2⁸ = 20781469 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20781691 and 20781700.

It is a congruent number.

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, 31499 + ... + 32151.

It is an arithmetic number, because the mean of its divisors is an integer number (1148860).

Almost surely, 2^20781725 is an apocalyptic number.

20781725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20781725 is a deficient number, since it is larger than the sum of its proper divisors (6790915).

20781725 is a wasteful number, since it uses less digits than its factorization.

20781725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 749 (or 744 counting only the distinct ones).

The product of its (nonzero) digits is 7840, while the sum is 32.

The square root of 20781725 is about 4558.6977307121. The cubic root of 20781725 is about 274.9332069188.

The spelling of 20781725 in words is "twenty million, seven hundred eighty-one thousand, seven hundred twenty-five".