21421285 has 16 divisors (see below), whose sum is σ = 26745840. Its totient is φ = 16450560.

The previous prime is 21421273. The next prime is 21421319. The reversal of 21421285 is 58212412.

It can be written as a sum of positive squares in 8 ways, for example, as 1760929 + 19660356 = 1327^2 + 4434^2 .

It is not a de Polignac number, because 21421285 - 2¹⁵ = 21388517 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 34639 + ... + 35251.

It is an arithmetic number, because the mean of its divisors is an integer number (1671615).

Almost surely, 2^21421285 is an apocalyptic number.

It is an amenable number.

21421285 is a deficient number, since it is larger than the sum of its proper divisors (5324555).

21421285 is a wasteful number, since it uses less digits than its factorization.

21421285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 888.

The product of its digits is 1280, while the sum is 25.

The square root of 21421285 is about 4628.3134077113. The cubic root of 21421285 is about 277.7251264060.

Adding to 21421285 its reverse (58212412), we get a palindrome (79633697).

The spelling of 21421285 in words is "twenty-one million, four hundred twenty-one thousand, two hundred eighty-five".