21718211641 has 27 divisors (see below), whose sum is σ = 26011021869. Its totient is φ = 18080653248.

The previous prime is 21718211629. The next prime is 21718211651. The reversal of 21718211641 is 14611281712.

The square root of 21718211641 is 147371.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 4 ways, for example, as 166797225 + 21551414416 = 12915^2 + 146804^2 .

It is not a de Polignac number, because 21718211641 - 2¹³ = 21718203449 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21718211597 and 21718211606.

It is not an unprimeable number, because it can be changed into a prime (21718211651) by changing a digit.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 38168805 + ... + 38169373.

Almost surely, 2^21718211641 is an apocalyptic number.

21718211641 is the 147371-st square number.

21718211641 is the 73686-th centered octagonal number.

It is an amenable number.

21718211641 is a deficient number, since it is larger than the sum of its proper divisors (4292810228).

21718211641 is an frugal number, since it uses more digits than its factorization.

21718211641 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1226 (or 613 counting only the distinct ones).

The product of its digits is 5376, while the sum is 34.

The spelling of 21718211641 in words is "twenty-one billion, seven hundred eighteen million, two hundred eleven thousand, six hundred forty-one".