20681557 has 32 divisors (see below), whose sum is σ = 25195520. Its totient is φ = 16796160.

The previous prime is 20681539. The next prime is 20681567. The reversal of 20681557 is 75518602.

It is a cyclic number.

It is not a de Polignac number, because 20681557 - 2¹¹ = 20679509 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20681567) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 283273 + ... + 283345.

It is an arithmetic number, because the mean of its divisors is an integer number (787360).

Almost surely, 2^20681557 is an apocalyptic number.

It is an amenable number.

20681557 is a deficient number, since it is larger than the sum of its proper divisors (4513963).

20681557 is a wasteful number, since it uses less digits than its factorization.

20681557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173.

The product of its (nonzero) digits is 16800, while the sum is 34.

The square root of 20681557 is about 4547.6979890929. The cubic root of 20681557 is about 274.4907689084.

The spelling of 20681557 in words is "twenty million, six hundred eighty-one thousand, five hundred fifty-seven".