20887817 has 4 divisors (see below), whose sum is σ = 21052416. Its totient is φ = 20723220.

The previous prime is 20887813. The next prime is 20887843. The reversal of 20887817 is 71878802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20887817 - 2² = 20887813 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20887813) 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 3 ways as a sum of consecutive naturals, for example, 82109 + ... + 82362.

It is an arithmetic number, because the mean of its divisors is an integer number (5263104).

Almost surely, 2^20887817 is an apocalyptic number.

It is an amenable number.

20887817 is a deficient number, since it is larger than the sum of its proper divisors (164599).

20887817 is a wasteful number, since it uses less digits than its factorization.

20887817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164598.

The product of its (nonzero) digits is 50176, while the sum is 41.

The square root of 20887817 is about 4570.3191354653. The cubic root of 20887817 is about 275.4002634136.

The spelling of 20887817 in words is "twenty million, eight hundred eighty-seven thousand, eight hundred seventeen".