21089725 has 6 divisors (see below), whose sum is σ = 26151290. Its totient is φ = 16871760.

The previous prime is 21089723. The next prime is 21089729. The reversal of 21089725 is 52798012.

It can be written as a sum of positive squares in 3 ways, for example, as 487204 + 20602521 = 698^2 + 4539^2 .

It is not a de Polignac number, because 21089725 - 2¹ = 21089723 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21089723) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 421770 + ... + 421819.

Almost surely, 2^21089725 is an apocalyptic number.

21089725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21089725 is a deficient number, since it is larger than the sum of its proper divisors (5061565).

21089725 is an equidigital number, since it uses as much as digits as its factorization.

21089725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 843599 (or 843594 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 34.

The square root of 21089725 is about 4592.3550603149. The cubic root of 21089725 is about 276.2847870854.

The spelling of 21089725 in words is "twenty-one million, eighty-nine thousand, seven hundred twenty-five".