21004755 has 16 divisors (see below), whose sum is σ = 33799680. Its totient is φ = 11138528.

The previous prime is 21004721. The next prime is 21004771. The reversal of 21004755 is 55740012.

It is a cyclic number.

It is not a de Polignac number, because 21004755 - 2⁶ = 21004691 is a prime.

It is a super-2 number, since 2×21004755² = 882399465220050, which contains 22 as substring.

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, 1227 + ... + 6596.

It is an arithmetic number, because the mean of its divisors is an integer number (2112480).

Almost surely, 2^21004755 is an apocalyptic number.

21004755 is a deficient number, since it is larger than the sum of its proper divisors (12794925).

21004755 is a wasteful number, since it uses less digits than its factorization.

21004755 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8010.

The product of its (nonzero) digits is 1400, while the sum is 24.

The square root of 21004755 is about 4583.0944786247. The cubic root of 21004755 is about 275.9132393753.

Adding to 21004755 its reverse (55740012), we get a palindrome (76744767).

The spelling of 21004755 in words is "twenty-one million, four thousand, seven hundred fifty-five".