21509722 has 16 divisors (see below), whose sum is σ = 35868672. Its totient is φ = 9606960.

The previous prime is 21509717. The next prime is 21509723. The reversal of 21509722 is 22790512.

It is not an unprimeable number, because it can be changed into a prime (21509723) 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, 12538 + ... + 14149.

It is an arithmetic number, because the mean of its divisors is an integer number (2241792).

Almost surely, 2^21509722 is an apocalyptic number.

21509722 is a deficient number, since it is larger than the sum of its proper divisors (14358950).

21509722 is a wasteful number, since it uses less digits than its factorization.

21509722 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26733.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21509722 is about 4637.8574794834. The cubic root of 21509722 is about 278.1067943644.

The spelling of 21509722 in words is "twenty-one million, five hundred nine thousand, seven hundred twenty-two".