21762921 has 4 divisors (see below), whose sum is σ = 29017232. Its totient is φ = 14508612.

The previous prime is 21762901. The next prime is 21762929. The reversal of 21762921 is 12926712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21762921 - 2⁵ = 21762889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21762929) 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 3 ways as a sum of consecutive naturals, for example, 3627151 + ... + 3627156.

It is an arithmetic number, because the mean of its divisors is an integer number (7254308).

Almost surely, 2^21762921 is an apocalyptic number.

It is an amenable number.

21762921 is a deficient number, since it is larger than the sum of its proper divisors (7254311).

21762921 is an equidigital number, since it uses as much as digits as its factorization.

21762921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7254310.

The product of its digits is 3024, while the sum is 30.

The square root of 21762921 is about 4665.0745974743. The cubic root of 21762921 is about 279.1937734823.

The spelling of 21762921 in words is "twenty-one million, seven hundred sixty-two thousand, nine hundred twenty-one".