20991522 has 8 divisors (see below), whose sum is σ = 41983056. Its totient is φ = 6997172.

The previous prime is 20991521. The next prime is 20991527. The reversal of 20991522 is 22519902.

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

20991522 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 20991522.

It is not an unprimeable number, because it can be changed into a prime (20991521) 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, 1749288 + ... + 1749299.

It is an arithmetic number, because the mean of its divisors is an integer number (5247882).

Almost surely, 2^20991522 is an apocalyptic number.

20991522 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

20991522 is a wasteful number, since it uses less digits than its factorization.

20991522 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3498592.

The product of its (nonzero) digits is 3240, while the sum is 30.

The square root of 20991522 is about 4581.6505759388. The cubic root of 20991522 is about 275.8552854040.

The spelling of 20991522 in words is "twenty million, nine hundred ninety-one thousand, five hundred twenty-two".