21025121 has 12 divisors (see below), whose sum is σ = 23260032. Its totient is φ = 18987696.

The previous prime is 21025117. The next prime is 21025127. The reversal of 21025121 is 12152012.

It is not a de Polignac number, because 21025121 - 2² = 21025117 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21025096 and 21025105.

It is not an unprimeable number, because it can be changed into a prime (21025127) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6620 + ... + 9266.

It is an arithmetic number, because the mean of its divisors is an integer number (1938336).

Almost surely, 2^21025121 is an apocalyptic number.

It is an amenable number.

21025121 is a deficient number, since it is larger than the sum of its proper divisors (2234911).

21025121 is a wasteful number, since it uses less digits than its factorization.

21025121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2720 (or 2707 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 14.

The square root of 21025121 is about 4585.3158015561. The cubic root of 21025121 is about 276.0023848075.

Adding to 21025121 its reverse (12152012), we get a palindrome (33177133).

It can be divided in two parts, 21025 and 121, that multiplied together give a square (2544025 = 1595²).

The spelling of 21025121 in words is "twenty-one million, twenty-five thousand, one hundred twenty-one".