21186740 has 48 divisors (see below), whose sum is σ = 45901632. Its totient is φ = 8211456.

The previous prime is 21186701. The next prime is 21186769. The reversal of 21186740 is 4768112.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 129899 + ... + 130061.

It is an arithmetic number, because the mean of its divisors is an integer number (956284).

Almost surely, 2^21186740 is an apocalyptic number.

21186740 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21186740 is an abundant number, since it is smaller than the sum of its proper divisors (24714892).

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

21186740 is a wasteful number, since it uses less digits than its factorization.

21186740 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336 (or 334 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 29.

The square root of 21186740 is about 4602.9056040723. The cubic root of 21186740 is about 276.7077856983.

The spelling of 21186740 in words is "twenty-one million, one hundred eighty-six thousand, seven hundred forty".