20613506 has 4 divisors (see below), whose sum is σ = 30920262. Its totient is φ = 10306752.

The previous prime is 20613491. The next prime is 20613533. The reversal of 20613506 is 60531602.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 60531602 = 2 ⋅30265801.

It can be written as a sum of positive squares in only one way, i.e., 11256025 + 9357481 = 3355^2 + 3059^2 .

It is a super-2 number, since 2×20613506² = 849833259224072, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5153375 + ... + 5153378.

Almost surely, 2^20613506 is an apocalyptic number.

20613506 is a deficient number, since it is larger than the sum of its proper divisors (10306756).

20613506 is a wasteful number, since it uses less digits than its factorization.

20613506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10306755.

The product of its (nonzero) digits is 1080, while the sum is 23.

The square root of 20613506 is about 4540.2099070417. The cubic root of 20613506 is about 274.1893748289.

The spelling of 20613506 in words is "twenty million, six hundred thirteen thousand, five hundred six".