21647140 has 24 divisors (see below), whose sum is σ = 47436480. Its totient is φ = 8282208.

The previous prime is 21647113. The next prime is 21647173. The reversal of 21647140 is 4174612.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23070 + ... + 23989.

It is an arithmetic number, because the mean of its divisors is an integer number (1976520).

Almost surely, 2^21647140 is an apocalyptic number.

21647140 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21647140 is an abundant number, since it is smaller than the sum of its proper divisors (25789340).

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

21647140 is a wasteful number, since it uses less digits than its factorization.

21647140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 47091 (or 47089 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21647140 is about 4652.6487079942. The cubic root of 21647140 is about 278.6977795694.

The spelling of 21647140 in words is "twenty-one million, six hundred forty-seven thousand, one hundred forty".