21900929 has 8 divisors (see below), whose sum is σ = 23043048. Its totient is φ = 20787840.

The previous prime is 21900883. The next prime is 21900937. The reversal of 21900929 is 92900912.

It can be written as a sum of positive squares in 4 ways, for example, as 2408704 + 19492225 = 1552^2 + 4415^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21900929 - 2¹⁶ = 21835393 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21900895 and 21900904.

It is not an unprimeable number, because it can be changed into a prime (21902929) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 5702 + ... + 8735.

It is an arithmetic number, because the mean of its divisors is an integer number (2880381).

Almost surely, 2^21900929 is an apocalyptic number.

It is an amenable number.

21900929 is a deficient number, since it is larger than the sum of its proper divisors (1142119).

21900929 is a wasteful number, since it uses less digits than its factorization.

21900929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14515.

The product of its (nonzero) digits is 2916, while the sum is 32.

The square root of 21900929 is about 4679.8428392415. The cubic root of 21900929 is about 279.7826927867.

The spelling of 21900929 in words is "twenty-one million, nine hundred thousand, nine hundred twenty-nine".