21344040 has 64 divisors (see below), whose sum is σ = 71150400. Its totient is φ = 5691456.

The previous prime is 21344033. The next prime is 21344051. The reversal of 21344040 is 4044312.

It is a Harshad number since it is a multiple of its sum of digits (18).

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, 8802 + ... + 10961.

It is an arithmetic number, because the mean of its divisors is an integer number (1111725).

Almost surely, 2^21344040 is an apocalyptic number.

21344040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21344040 is an abundant number, since it is smaller than the sum of its proper divisors (49806360).

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

21344040 is a wasteful number, since it uses less digits than its factorization.

21344040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19783 (or 19773 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21344040 is about 4619.9610387968. The cubic root of 21344040 is about 277.3908994058.

Adding to 21344040 its reverse (4044312), we get a palindrome (25388352).

It can be divided in two parts, 213 and 44040, that added together give a triangular number (44253 = T₂₉₇).

The spelling of 21344040 in words is "twenty-one million, three hundred forty-four thousand, forty".