21710121 has 4 divisors (see below), whose sum is σ = 28946832. Its totient is φ = 14473412.

The previous prime is 21710113. The next prime is 21710123. The reversal of 21710121 is 12101712.

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 21710121 - 2³ = 21710113 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21710121.

It is not an unprimeable number, because it can be changed into a prime (21710123) 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, 3618351 + ... + 3618356.

It is an arithmetic number, because the mean of its divisors is an integer number (7236708).

Almost surely, 2^21710121 is an apocalyptic number.

It is an amenable number.

21710121 is a deficient number, since it is larger than the sum of its proper divisors (7236711).

21710121 is an equidigital number, since it uses as much as digits as its factorization.

21710121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7236710.

The product of its (nonzero) digits is 28, while the sum is 15.

The square root of 21710121 is about 4659.4120873775. The cubic root of 21710121 is about 278.9678024534.

Adding to 21710121 its reverse (12101712), we get a palindrome (33811833).

The spelling of 21710121 in words is "twenty-one million, seven hundred ten thousand, one hundred twenty-one".