21311641 has 4 divisors (see below), whose sum is σ = 22951012. Its totient is φ = 19672272.

The previous prime is 21311629. The next prime is 21311683. The reversal of 21311641 is 14611312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5271616 + 16040025 = 2296^2 + 4005^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21311641 is a prime.

It is a super-2 number, since 2×21311641² = 908372084225762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21311611) 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, 819666 + ... + 819691.

It is an arithmetic number, because the mean of its divisors is an integer number (5737753).

Almost surely, 2^21311641 is an apocalyptic number.

It is an amenable number.

21311641 is a deficient number, since it is larger than the sum of its proper divisors (1639371).

21311641 is a wasteful number, since it uses less digits than its factorization.

21311641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1639370.

The product of its digits is 144, while the sum is 19.

The square root of 21311641 is about 4616.4532923014. The cubic root of 21311641 is about 277.2504739610.

Adding to 21311641 its reverse (14611312), we get a palindrome (35922953).

It can be divided in two parts, 21311 and 641, that added together give a cube (21952 = 28³).

The spelling of 21311641 in words is "twenty-one million, three hundred eleven thousand, six hundred forty-one".