20987065 has 16 divisors (see below), whose sum is σ = 27654336. Its totient is φ = 15163200.

The previous prime is 20987059. The next prime is 20987069. The reversal of 20987065 is 56078902.

20987065 = 69² + 70² + ... + 398².

It is not a de Polignac number, because 20987065 - 2⁵ = 20987033 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20987069) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7795 + ... + 10135.

It is an arithmetic number, because the mean of its divisors is an integer number (1728396).

Almost surely, 2^20987065 is an apocalyptic number.

It is an amenable number.

20987065 is a deficient number, since it is larger than the sum of its proper divisors (6667271).

20987065 is a wasteful number, since it uses less digits than its factorization.

20987065 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2520.

The product of its (nonzero) digits is 30240, while the sum is 37.

The square root of 20987065 is about 4581.1641533567. The cubic root of 20987065 is about 275.8357604733.

The spelling of 20987065 in words is "twenty million, nine hundred eighty-seven thousand, sixty-five".