20987711 has 2 divisors, whose sum is σ = 20987712. Its totient is φ = 20987710.

The previous prime is 20987627. The next prime is 20987731. The reversal of 20987711 is 11778902.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20987711 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20987731) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10493855 + 10493856.

It is an arithmetic number, because the mean of its divisors is an integer number (10493856).

Almost surely, 2^20987711 is an apocalyptic number.

20987711 is a deficient number, since it is larger than the sum of its proper divisors (1).

20987711 is an equidigital number, since it uses as much as digits as its factorization.

20987711 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 7056, while the sum is 35.

The square root of 20987711 is about 4581.2346589102. The cubic root of 20987711 is about 275.8385905986.

The spelling of 20987711 in words is "twenty million, nine hundred eighty-seven thousand, seven hundred eleven".