21702121 has 8 divisors (see below), whose sum is σ = 25657920. Its totient is φ = 17960208.

The previous prime is 21702103. The next prime is 21702157. The reversal of 21702121 is 12120712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21702121 - 2⁵ = 21702089 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21702095 and 21702104.

It is not an unprimeable number, because it can be changed into a prime (21702221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 53251 + ... + 53656.

It is an arithmetic number, because the mean of its divisors is an integer number (3207240).

Almost surely, 2^21702121 is an apocalyptic number.

It is an amenable number.

21702121 is a deficient number, since it is larger than the sum of its proper divisors (3955799).

21702121 is a wasteful number, since it uses less digits than its factorization.

21702121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106943.

The product of its (nonzero) digits is 56, while the sum is 16.

The square root of 21702121 is about 4658.5535308720. The cubic root of 21702121 is about 278.9335324678.

Adding to 21702121 its reverse (12120712), we get a palindrome (33822833).

The spelling of 21702121 in words is "twenty-one million, seven hundred two thousand, one hundred twenty-one".