21001611 has 8 divisors (see below), whose sum is σ = 28157584. Its totient is φ = 13923360.

The previous prime is 21001577. The next prime is 21001627. The reversal of 21001611 is 11610012.

It is a happy number.

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

It is not a de Polignac number, because 21001611 - 2¹⁴ = 20985227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21001411) 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, 18796 + ... + 19881.

It is an arithmetic number, because the mean of its divisors is an integer number (3519698).

Almost surely, 2^21001611 is an apocalyptic number.

21001611 is a deficient number, since it is larger than the sum of its proper divisors (7155973).

21001611 is a wasteful number, since it uses less digits than its factorization.

21001611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38861.

The product of its (nonzero) digits is 12, while the sum is 12.

The square root of 21001611 is about 4582.7514660955. The cubic root of 21001611 is about 275.8994724210.

Adding to 21001611 its reverse (11610012), we get a palindrome (32611623).

It can be divided in two parts, 21001 and 611, that added together give a palindrome (21612).

The spelling of 21001611 in words is "twenty-one million, one thousand, six hundred eleven".