21325287 has 4 divisors (see below), whose sum is σ = 28433720. Its totient is φ = 14216856.

The previous prime is 21325279. The next prime is 21325307. The reversal of 21325287 is 78252312.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21325287 - 2³ = 21325279 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21325217) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3554212 + ... + 3554217.

It is an arithmetic number, because the mean of its divisors is an integer number (7108430).

Almost surely, 2^21325287 is an apocalyptic number.

21325287 is a deficient number, since it is larger than the sum of its proper divisors (7108433).

21325287 is an equidigital number, since it uses as much as digits as its factorization.

21325287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7108432.

The product of its digits is 6720, while the sum is 30.

The square root of 21325287 is about 4617.9310302342. The cubic root of 21325287 is about 277.3096365059.

Adding to 21325287 its reverse (78252312), we get a palindrome (99577599).

Subtracting 21325287 from its reverse (78252312), we obtain a square (56927025 = 7545²).

It can be divided in two parts, 21325 and 287, that added together give a palindrome (21612).

The spelling of 21325287 in words is "twenty-one million, three hundred twenty-five thousand, two hundred eighty-seven".