20561057 has 16 divisors (see below), whose sum is σ = 23587200. Its totient is φ = 17740800.

The previous prime is 20561053. The next prime is 20561069. The reversal of 20561057 is 75016502.

It is not a de Polignac number, because 20561057 - 2² = 20561053 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20561053) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 45569 + ... + 46017.

It is an arithmetic number, because the mean of its divisors is an integer number (1474200).

Almost surely, 2^20561057 is an apocalyptic number.

It is an amenable number.

20561057 is a deficient number, since it is larger than the sum of its proper divisors (3026143).

20561057 is a wasteful number, since it uses less digits than its factorization.

20561057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 664.

The product of its (nonzero) digits is 2100, while the sum is 26.

The square root of 20561057 is about 4534.4301736822. The cubic root of 20561057 is about 273.9566281892.

Adding to 20561057 its reverse (75016502), we get a palindrome (95577559).

Subtracting 20561057 from its reverse (75016502), we obtain a palindrome (54455445).

It can be divided in two parts, 2056 and 1057, that added together give a palindrome (3113).

The spelling of 20561057 in words is "twenty million, five hundred sixty-one thousand, fifty-seven".