21572516 has 12 divisors (see below), whose sum is σ = 43145088. Its totient is φ = 9245352.

The previous prime is 21572513. The next prime is 21572521. The reversal of 21572516 is 61527512.

21572516 is an admirable number.

It is not an unprimeable number, because it can be changed into a prime (21572513) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 385196 + ... + 385251.

It is an arithmetic number, because the mean of its divisors is an integer number (3595424).

Almost surely, 2^21572516 is an apocalyptic number.

It is an amenable number.

21572516 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.

21572516 is a wasteful number, since it uses less digits than its factorization.

21572516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 770458 (or 770456 counting only the distinct ones).

The product of its digits is 4200, while the sum is 29.

The square root of 21572516 is about 4644.6222666650. The cubic root of 21572516 is about 278.3771600422.

The spelling of 21572516 in words is "twenty-one million, five hundred seventy-two thousand, five hundred sixteen".