21016725 has 12 divisors (see below), whose sum is σ = 34747776. Its totient is φ = 11208880.

The previous prime is 21016693. The next prime is 21016739. The reversal of 21016725 is 52761012.

It is not a de Polignac number, because 21016725 - 2⁵ = 21016693 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 = 21016695 and 21016704.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 140037 + ... + 140186.

It is an arithmetic number, because the mean of its divisors is an integer number (2895648).

Almost surely, 2^21016725 is an apocalyptic number.

21016725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21016725 is a deficient number, since it is larger than the sum of its proper divisors (13731051).

21016725 is a wasteful number, since it uses less digits than its factorization.

21016725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280236 (or 280231 counting only the distinct ones).

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 21016725 is about 4584.4001788675. The cubic root of 21016725 is about 275.9656410705.

Adding to 21016725 its reverse (52761012), we get a palindrome (73777737).

The spelling of 21016725 in words is "twenty-one million, sixteen thousand, seven hundred twenty-five".