21022704 has 30 divisors (see below), whose sum is σ = 58834776. Its totient is φ = 7007520.

The previous prime is 21022699. The next prime is 21022711. The reversal of 21022704 is 40722012.

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

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 72852 + ... + 73139.

Almost surely, 2^21022704 is an apocalyptic number.

21022704 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21022704 is an abundant number, since it is smaller than the sum of its proper divisors (37812072).

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

21022704 is a wasteful number, since it uses less digits than its factorization.

21022704 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146005 (or 145996 counting only the distinct ones).

The product of its (nonzero) digits is 224, while the sum is 18.

The square root of 21022704 is about 4585.0522352532. The cubic root of 21022704 is about 275.9918082005.

Adding to 21022704 its reverse (40722012), we get a palindrome (61744716).

The spelling of 21022704 in words is "twenty-one million, twenty-two thousand, seven hundred four".