21156711 has 16 divisors (see below), whose sum is σ = 30234624. Its totient is φ = 13125024.

The previous prime is 21156703. The next prime is 21156713. The reversal of 21156711 is 11765112.

It is not a de Polignac number, because 21156711 - 2³ = 21156703 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156713) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 1591 + ... + 6696.

It is an arithmetic number, because the mean of its divisors is an integer number (1889664).

Almost surely, 2^21156711 is an apocalyptic number.

21156711 is a deficient number, since it is larger than the sum of its proper divisors (9077913).

21156711 is a wasteful number, since it uses less digits than its factorization.

21156711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8350.

The product of its digits is 420, while the sum is 24.

The square root of 21156711 is about 4599.6424861069. The cubic root of 21156711 is about 276.5769934056.

The spelling of 21156711 in words is "twenty-one million, one hundred fifty-six thousand, seven hundred eleven".