21471921621 has 12 divisors (see below), whose sum is σ = 32839409772. Its totient is φ = 13472578176.

The previous prime is 21471921619. The next prime is 21471921727. The reversal of 21471921621 is 12612917412.

21471921621 is a `hidden beast` number, since 2 + 1 + 4 + 7 + 1 + 9 + 21 + 621 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 7497135396 + 13974786225 = 86586^2 + 118215^2 .

It is not a de Polignac number, because 21471921621 - 2¹ = 21471921619 is a prime.

It is a super-2 number, since 2×21471921621² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21471921521) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 70169526 + ... + 70169831.

It is an arithmetic number, because the mean of its divisors is an integer number (2736617481).

Almost surely, 2^21471921621 is an apocalyptic number.

It is an amenable number.

21471921621 is a deficient number, since it is larger than the sum of its proper divisors (11367488151).

21471921621 is a wasteful number, since it uses less digits than its factorization.

21471921621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140339380 (or 140339377 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The spelling of 21471921621 in words is "twenty-one billion, four hundred seventy-one million, nine hundred twenty-one thousand, six hundred twenty-one".