21985711 has 4 divisors (see below), whose sum is σ = 23984424. Its totient is φ = 19987000.

The previous prime is 21985703. The next prime is 21985753. The reversal of 21985711 is 11758912.

It is a happy number.

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

It is not a de Polignac number, because 21985711 - 2³ = 21985703 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21985211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 999340 + ... + 999361.

It is an arithmetic number, because the mean of its divisors is an integer number (5996106).

Almost surely, 2^21985711 is an apocalyptic number.

21985711 is a deficient number, since it is larger than the sum of its proper divisors (1998713).

21985711 is a wasteful number, since it uses less digits than its factorization.

21985711 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1998712.

The product of its digits is 5040, while the sum is 34.

The square root of 21985711 is about 4688.8922998934. The cubic root of 21985711 is about 280.1432557755.

The spelling of 21985711 in words is "twenty-one million, nine hundred eighty-five thousand, seven hundred eleven".