21725837 has 4 divisors (see below), whose sum is σ = 24829536. Its totient is φ = 18622140.

The previous prime is 21725833. The next prime is 21725849. The reversal of 21725837 is 73852712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21725837 - 2² = 21725833 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21725797 and 21725806.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21725833) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1551839 + ... + 1551852.

It is an arithmetic number, because the mean of its divisors is an integer number (6207384).

Almost surely, 2^21725837 is an apocalyptic number.

It is an amenable number.

21725837 is a deficient number, since it is larger than the sum of its proper divisors (3103699).

21725837 is an equidigital number, since it uses as much as digits as its factorization.

21725837 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3103698.

The product of its digits is 23520, while the sum is 35.

The square root of 21725837 is about 4661.0982611397. The cubic root of 21725837 is about 279.0351013334.

The spelling of 21725837 in words is "twenty-one million, seven hundred twenty-five thousand, eight hundred thirty-seven".