21421275 has 48 divisors (see below), whose sum is σ = 38327904. Its totient is φ = 10516480.

The previous prime is 21421273. The next prime is 21421319. The reversal of 21421275 is 57212412.

It is not a de Polignac number, because 21421275 - 2¹ = 21421273 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21421273) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 67417 + ... + 67733.

It is an arithmetic number, because the mean of its divisors is an integer number (798498).

Almost surely, 2^21421275 is an apocalyptic number.

21421275 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21421275 is a deficient number, since it is larger than the sum of its proper divisors (16906629).

21421275 is a wasteful number, since it uses less digits than its factorization.

21421275 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 400 (or 395 counting only the distinct ones).

The product of its digits is 1120, while the sum is 24.

The square root of 21421275 is about 4628.3123274040. The cubic root of 21421275 is about 277.7250831896.

Adding to 21421275 its reverse (57212412), we get a palindrome (78633687).

The spelling of 21421275 in words is "twenty-one million, four hundred twenty-one thousand, two hundred seventy-five".