21711740 has 12 divisors (see below), whose sum is σ = 45594696. Its totient is φ = 8684688.

The previous prime is 21711731. The next prime is 21711757. The reversal of 21711740 is 4711712.

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, 542774 + ... + 542813.

It is an arithmetic number, because the mean of its divisors is an integer number (3799558).

Almost surely, 2^21711740 is an apocalyptic number.

21711740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21711740 is an abundant number, since it is smaller than the sum of its proper divisors (23882956).

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

21711740 is a wasteful number, since it uses less digits than its factorization.

21711740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1085596 (or 1085594 counting only the distinct ones).

The product of its (nonzero) digits is 392, while the sum is 23.

The square root of 21711740 is about 4659.5858185036. The cubic root of 21711740 is about 278.9747368174.

The spelling of 21711740 in words is "twenty-one million, seven hundred eleven thousand, seven hundred forty".