20725213 has 4 divisors (see below), whose sum is σ = 21230748. Its totient is φ = 20219680.

The previous prime is 20725171. The next prime is 20725241. The reversal of 20725213 is 31252702.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 412164 + 20313049 = 642^2 + 4507^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20725213 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 (20725273) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 252706 + ... + 252787.

It is an arithmetic number, because the mean of its divisors is an integer number (5307687).

Almost surely, 2^20725213 is an apocalyptic number.

It is an amenable number.

20725213 is a deficient number, since it is larger than the sum of its proper divisors (505535).

20725213 is an equidigital number, since it uses as much as digits as its factorization.

20725213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 505534.

The product of its (nonzero) digits is 840, while the sum is 22.

The square root of 20725213 is about 4552.4952498602. The cubic root of 20725213 is about 274.6837709353.

Adding to 20725213 its reverse (31252702), we get a palindrome (51977915).

The spelling of 20725213 in words is "twenty million, seven hundred twenty-five thousand, two hundred thirteen".