20213537 has 6 divisors (see below), whose sum is σ = 20358774. Its totient is φ = 20069280.

The previous prime is 20213503. The next prime is 20213563. The reversal of 20213537 is 73531202.

It can be written as a sum of positive squares in 3 ways, for example, as 6345361 + 13868176 = 2519^2 + 3724^2 .

It is not a de Polignac number, because 20213537 - 2²⁰ = 19164961 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20213437) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32453 + ... + 33069.

It is an arithmetic number, because the mean of its divisors is an integer number (3393129).

Almost surely, 2^20213537 is an apocalyptic number.

It is an amenable number.

20213537 is a deficient number, since it is larger than the sum of its proper divisors (145237).

20213537 is an frugal number, since it uses more digits than its factorization.

20213537 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 979 (or 798 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 20213537 is about 4495.9467301115. The cubic root of 20213537 is about 272.4043914513.

Adding to 20213537 its reverse (73531202), we get a palindrome (93744739).

The spelling of 20213537 in words is "twenty million, two hundred thirteen thousand, five hundred thirty-seven".