20987755 has 8 divisors (see below), whose sum is σ = 25210224. Its totient is φ = 16773600.

The previous prime is 20987737. The next prime is 20987767. The reversal of 20987755 is 55778902.

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

It is not a de Polignac number, because 20987755 - 2⁷ = 20987627 is a prime.

It is a Duffinian number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 7500 + ... + 9910.

It is an arithmetic number, because the mean of its divisors is an integer number (3151278).

Almost surely, 2^20987755 is an apocalyptic number.

20987755 is a deficient number, since it is larger than the sum of its proper divisors (4222469).

20987755 is a wasteful number, since it uses less digits than its factorization.

20987755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4157.

The product of its (nonzero) digits is 176400, while the sum is 43.

The square root of 20987755 is about 4581.2394611066. The cubic root of 20987755 is about 275.8387833605.

The spelling of 20987755 in words is "twenty million, nine hundred eighty-seven thousand, seven hundred fifty-five".