21921010 has 8 divisors (see below), whose sum is σ = 39457836. Its totient is φ = 8768400.

The previous prime is 21920989. The next prime is 21921017. The reversal of 21921010 is 1012912.

It can be written as a sum of positive squares in 2 ways, for example, as 21520321 + 400689 = 4639^2 + 633^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21921017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1096041 + ... + 1096060.

Almost surely, 2^21921010 is an apocalyptic number.

21921010 is a deficient number, since it is larger than the sum of its proper divisors (17536826).

21921010 is a wasteful number, since it uses less digits than its factorization.

21921010 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2192108.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 21921010 is about 4681.9878256997. The cubic root of 21921010 is about 279.8681777446.

Adding to 21921010 its reverse (1012912), we get a palindrome (22933922).

The spelling of 21921010 in words is "twenty-one million, nine hundred twenty-one thousand, ten".