21252385 has 16 divisors (see below), whose sum is σ = 31796352. Its totient is φ = 13248000.

The previous prime is 21252383. The next prime is 21252401. The reversal of 21252385 is 58325212.

21252385 = 15² + 16² + ... + 399².

It is not a de Polignac number, because 21252385 - 2¹ = 21252383 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is not an unprimeable number, because it can be changed into a prime (21252383) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27216 + ... + 27985.

It is an arithmetic number, because the mean of its divisors is an integer number (1987272).

Almost surely, 2^21252385 is an apocalyptic number.

It is an amenable number.

21252385 is a deficient number, since it is larger than the sum of its proper divisors (10543967).

21252385 is a wasteful number, since it uses less digits than its factorization.

21252385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55224.

The product of its digits is 4800, while the sum is 28.

The square root of 21252385 is about 4610.0309109593. The cubic root of 21252385 is about 276.9932748696.

Adding to 21252385 its reverse (58325212), we get a palindrome (79577597).

The spelling of 21252385 in words is "twenty-one million, two hundred fifty-two thousand, three hundred eighty-five".