21013725 has 12 divisors (see below), whose sum is σ = 34742816. Its totient is φ = 11207280.

The previous prime is 21013723. The next prime is 21013781. The reversal of 21013725 is 52731012.

It is not a de Polignac number, because 21013725 - 2¹ = 21013723 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21013723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 140017 + ... + 140166.

Almost surely, 2^21013725 is an apocalyptic number.

21013725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21013725 is a deficient number, since it is larger than the sum of its proper divisors (13729091).

21013725 is a wasteful number, since it uses less digits than its factorization.

21013725 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280196 (or 280191 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 21013725 is about 4584.0729706234. The cubic root of 21013725 is about 275.9525096824.

Adding to 21013725 its reverse (52731012), we get a palindrome (73744737).

The spelling of 21013725 in words is "twenty-one million, thirteen thousand, seven hundred twenty-five".