21711440 has 20 divisors (see below), whose sum is σ = 50479284. Its totient is φ = 8684544.

The previous prime is 21711421. The next prime is 21711451. The reversal of 21711440 is 4411712.

It can be written as a sum of positive squares in 2 ways, for example, as 4999696 + 16711744 = 2236^2 + 4088^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135617 + ... + 135776.

Almost surely, 2^21711440 is an apocalyptic number.

21711440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21711440 is an abundant number, since it is smaller than the sum of its proper divisors (28767844).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21711440 is a wasteful number, since it uses less digits than its factorization.

21711440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 271406 (or 271400 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 20.

The square root of 21711440 is about 4659.5536266900. The cubic root of 21711440 is about 278.9734519088.

The spelling of 21711440 in words is "twenty-one million, seven hundred eleven thousand, four hundred forty".