20691925 has 6 divisors (see below), whose sum is σ = 25658018. Its totient is φ = 16553520.

The previous prime is 20691919. The next prime is 20691929. The reversal of 20691925 is 52919602.

It can be written as a sum of positive squares in 3 ways, for example, as 4835601 + 15856324 = 2199^2 + 3982^2 .

It is not a de Polignac number, because 20691925 - 2¹⁷ = 20560853 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20691929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 413814 + ... + 413863.

Almost surely, 2^20691925 is an apocalyptic number.

20691925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

20691925 is a deficient number, since it is larger than the sum of its proper divisors (4966093).

20691925 is an equidigital number, since it uses as much as digits as its factorization.

20691925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 827687 (or 827682 counting only the distinct ones).

The product of its (nonzero) digits is 9720, while the sum is 34.

The square root of 20691925 is about 4548.8377636491. The cubic root of 20691925 is about 274.5366301373.

The spelling of 20691925 in words is "twenty million, six hundred ninety-one thousand, nine hundred twenty-five".