20981057 has 8 divisors (see below), whose sum is σ = 21651840. Its totient is φ = 20320560.

The previous prime is 20981047. The next prime is 20981063. The reversal of 20981057 is 75018902.

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

It is a cyclic number.

It is not a de Polignac number, because 20981057 - 2⁴ = 20981041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20981027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1682 + ... + 6692.

It is an arithmetic number, because the mean of its divisors is an integer number (2706480).

Almost surely, 2^20981057 is an apocalyptic number.

It is an amenable number.

20981057 is a deficient number, since it is larger than the sum of its proper divisors (670783).

20981057 is an equidigital number, since it uses as much as digits as its factorization.

20981057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5143.

The product of its (nonzero) digits is 5040, while the sum is 32.

The square root of 20981057 is about 4580.5083778987. The cubic root of 20981057 is about 275.8094366494.

Adding to 20981057 its reverse (75018902), we get a palindrome (95999959).

The spelling of 20981057 in words is "twenty million, nine hundred eighty-one thousand, fifty-seven".