20990506 has 8 divisors (see below), whose sum is σ = 31600260. Its totient is φ = 10457088.

The previous prime is 20990479. The next prime is 20990521. The reversal of 20990506 is 60509902.

It can be written as a sum of positive squares in 2 ways, for example, as 18844281 + 2146225 = 4341^2 + 1465^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18391 + ... + 19498.

Almost surely, 2^20990506 is an apocalyptic number.

20990506 is a deficient number, since it is larger than the sum of its proper divisors (10609754).

20990506 is a wasteful number, since it uses less digits than its factorization.

20990506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38168.

The product of its (nonzero) digits is 4860, while the sum is 31.

The square root of 20990506 is about 4581.5396975253. The cubic root of 20990506 is about 275.8508348216.

The spelling of 20990506 in words is "twenty million, nine hundred ninety thousand, five hundred six".