21004344 has 24 divisors (see below), whose sum is σ = 56886960. Its totient is φ = 7001424.

The previous prime is 21004331. The next prime is 21004351. The reversal of 21004344 is 44340012.

It is a tau number, because it is divible by the number of its divisors (24).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 145792 + ... + 145935.

It is an arithmetic number, because the mean of its divisors is an integer number (2370290).

Almost surely, 2^21004344 is an apocalyptic number.

21004344 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21004344 is an abundant number, since it is smaller than the sum of its proper divisors (35882616).

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

21004344 is a wasteful number, since it uses less digits than its factorization.

21004344 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 291739 (or 291732 counting only the distinct ones).

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

The square root of 21004344 is about 4583.0496397050. The cubic root of 21004344 is about 275.9114397656.

Adding to 21004344 its reverse (44340012), we get a palindrome (65344356).

The spelling of 21004344 in words is "twenty-one million, four thousand, three hundred forty-four".