21125245 has 16 divisors (see below), whose sum is σ = 27144000. Its totient is φ = 15735168.

The previous prime is 21125239. The next prime is 21125257. The reversal of 21125245 is 54252112.

It is a cyclic number.

It is not a de Polignac number, because 21125245 - 2²³ = 12736637 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, 3721 + ... + 7489.

It is an arithmetic number, because the mean of its divisors is an integer number (1696500).

Almost surely, 2^21125245 is an apocalyptic number.

It is an amenable number.

21125245 is a deficient number, since it is larger than the sum of its proper divisors (6018755).

21125245 is a wasteful number, since it uses less digits than its factorization.

21125245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3852.

The product of its digits is 800, while the sum is 22.

The square root of 21125245 is about 4596.2207301217. The cubic root of 21125245 is about 276.4398093582.

Adding to 21125245 its reverse (54252112), we get a palindrome (75377357).

It can be divided in two parts, 21125 and 245, that multiplied together give a square (5175625 = 2275²).

The spelling of 21125245 in words is "twenty-one million, one hundred twenty-five thousand, two hundred forty-five".