21436925 has 12 divisors (see below), whose sum is σ = 27019476. Its totient is φ = 16867200.

The previous prime is 21436873. The next prime is 21436927. The reversal of 21436925 is 52963412.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 9897316 + 11539609 = 3146^2 + 3397^2 .

It is not a de Polignac number, because 21436925 - 2¹⁴ = 21420541 is a prime.

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

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21436891 and 21436900.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21436927) 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, 5504 + ... + 8553.

It is an arithmetic number, because the mean of its divisors is an integer number (2251623).

Almost surely, 2^21436925 is an apocalyptic number.

21436925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21436925 is a deficient number, since it is larger than the sum of its proper divisors (5582551).

21436925 is a wasteful number, since it uses less digits than its factorization.

21436925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14128 (or 14123 counting only the distinct ones).

The product of its digits is 12960, while the sum is 32.

The square root of 21436925 is about 4630.0026997832. The cubic root of 21436925 is about 277.7927003835.

It can be divided in two parts, 214369 and 25, that multiplied together give a square (5359225 = 2315²).

The spelling of 21436925 in words is "twenty-one million, four hundred thirty-six thousand, nine hundred twenty-five".