20987924 has 6 divisors (see below), whose sum is σ = 36728874. Its totient is φ = 10493960.

The previous prime is 20987921. The next prime is 20987927. The reversal of 20987924 is 42978902.

It is an interprime number because it is at equal distance from previous prime (20987921) and next prime (20987927).

It can be written as a sum of positive squares in only one way, i.e., 20539024 + 448900 = 4532^2 + 670^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20987921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2623487 + ... + 2623494.

It is an arithmetic number, because the mean of its divisors is an integer number (6121479).

Almost surely, 2^20987924 is an apocalyptic number.

It is an amenable number.

20987924 is a deficient number, since it is larger than the sum of its proper divisors (15740950).

20987924 is a wasteful number, since it uses less digits than its factorization.

20987924 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5246985 (or 5246983 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 41.

The square root of 20987924 is about 4581.2579058595. The cubic root of 20987924 is about 275.8395237387.

The spelling of 20987924 in words is "twenty million, nine hundred eighty-seven thousand, nine hundred twenty-four".