21124025 has 12 divisors (see below), whose sum is σ = 28209132. Its totient is φ = 15599040.

The previous prime is 21124021. The next prime is 21124031. The reversal of 21124025 is 52042112.

It can be written as a sum of positive squares in 6 ways, for example, as 5851561 + 15272464 = 2419^2 + 3908^2 .

It is not a de Polignac number, because 21124025 - 2² = 21124021 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21123994 and 21124012.

It is not an unprimeable number, because it can be changed into a prime (21124021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 32174 + ... + 32823.

It is an arithmetic number, because the mean of its divisors is an integer number (2350761).

Almost surely, 2^21124025 is an apocalyptic number.

21124025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21124025 is a deficient number, since it is larger than the sum of its proper divisors (7085107).

21124025 is a wasteful number, since it uses less digits than its factorization.

21124025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65020 (or 65015 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21124025 is about 4596.0880104715. The cubic root of 21124025 is about 276.4344877148.

Adding to 21124025 its reverse (52042112), we get a palindrome (73166137).

The spelling of 21124025 in words is "twenty-one million, one hundred twenty-four thousand, twenty-five".