21250725 has 24 divisors (see below), whose sum is σ = 35667360. Its totient is φ = 11161920.

The previous prime is 21250709. The next prime is 21250771. The reversal of 21250725 is 52705212.

It is not a de Polignac number, because 21250725 - 2⁴ = 21250709 is a prime.

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

It is a junction number, because it is equal to n+sod(n) for n = 21250695 and 21250704.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2911 + ... + 7139.

It is an arithmetic number, because the mean of its divisors is an integer number (1486140).

Almost surely, 2^21250725 is an apocalyptic number.

21250725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21250725 is a deficient number, since it is larger than the sum of its proper divisors (14416635).

21250725 is a wasteful number, since it uses less digits than its factorization.

21250725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4309 (or 4304 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21250725 is about 4609.8508652667. The cubic root of 21250725 is about 276.9860628037.

Adding to 21250725 its reverse (52705212), we get a palindrome (73955937).

The spelling of 21250725 in words is "twenty-one million, two hundred fifty thousand, seven hundred twenty-five".