21022749 has 24 divisors (see below), whose sum is σ = 33400224. Its totient is φ = 12636000.

The previous prime is 21022741. The next prime is 21022753. The reversal of 21022749 is 94722012.

It is not a de Polignac number, because 21022749 - 2³ = 21022741 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21022741) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 12159 + ... + 13779.

It is an arithmetic number, because the mean of its divisors is an integer number (1391676).

Almost surely, 2^21022749 is an apocalyptic number.

It is an amenable number.

21022749 is a deficient number, since it is larger than the sum of its proper divisors (12377475).

21022749 is a wasteful number, since it uses less digits than its factorization.

21022749 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1769 (or 1766 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21022749 is about 4585.0571425011. The cubic root of 21022749 is about 275.9920051244.

It can be divided in two parts, 210227 and 49, that added together give a triangular number (210276 = T₆₄₈).

The spelling of 21022749 in words is "twenty-one million, twenty-two thousand, seven hundred forty-nine".