20981571 has 16 divisors (see below), whose sum is σ = 30266880. Its totient is φ = 12852000.

The previous prime is 20981561. The next prime is 20981573. The reversal of 20981571 is 17518902.

It is not a de Polignac number, because 20981571 - 2⁶ = 20981507 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20981573) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8196 + ... + 10446.

It is an arithmetic number, because the mean of its divisors is an integer number (1891680).

Almost surely, 2^20981571 is an apocalyptic number.

20981571 is a deficient number, since it is larger than the sum of its proper divisors (9285309).

20981571 is a wasteful number, since it uses less digits than its factorization.

20981571 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2506.

The product of its (nonzero) digits is 5040, while the sum is 33.

The square root of 20981571 is about 4580.5644848643. The cubic root of 20981571 is about 275.8116889174.

The spelling of 20981571 in words is "twenty million, nine hundred eighty-one thousand, five hundred seventy-one".