20881618 has 4 divisors (see below), whose sum is σ = 31322430. Its totient is φ = 10440808.

The previous prime is 20881613. The next prime is 20881633. The reversal of 20881618 is 81618802.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 19686969 + 1194649 = 4437^2 + 1093^2 .

It is not an unprimeable number, because it can be changed into a prime (20881613) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5220403 + ... + 5220406.

Almost surely, 2^20881618 is an apocalyptic number.

20881618 is a deficient number, since it is larger than the sum of its proper divisors (10440812).

20881618 is a wasteful number, since it uses less digits than its factorization.

20881618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10440811.

The product of its (nonzero) digits is 6144, while the sum is 34.

The square root of 20881618 is about 4569.6409049290. The cubic root of 20881618 is about 275.3730166674.

The spelling of 20881618 in words is "twenty million, eight hundred eighty-one thousand, six hundred eighteen".