20987011 has 4 divisors (see below), whose sum is σ = 21023352. Its totient is φ = 20950672.

The previous prime is 20986991. The next prime is 20987023. The reversal of 20987011 is 11078902.

20987011 = T₃₇₃₉ + T₃₇₄₀ + T₃₇₄₁.

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

It is a cyclic number.

It is not a de Polignac number, because 20987011 - 2⁷ = 20986883 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20987041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17290 + ... + 18463.

It is an arithmetic number, because the mean of its divisors is an integer number (5255838).

Almost surely, 2^20987011 is an apocalyptic number.

20987011 is the 3741-st centered triangular number.

20987011 is a deficient number, since it is larger than the sum of its proper divisors (36341).

20987011 is an equidigital number, since it uses as much as digits as its factorization.

20987011 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36340.

The product of its (nonzero) digits is 1008, while the sum is 28.

The square root of 20987011 is about 4581.1582596544. The cubic root of 20987011 is about 275.8355238967.

The spelling of 20987011 in words is "twenty million, nine hundred eighty-seven thousand, eleven".