21006834381 has 64 divisors (see below), whose sum is σ = 34333286400. Its totient is φ = 12613434048.

The previous prime is 21006834367. The next prime is 21006834403. The reversal of 21006834381 is 18343860012.

21006834381 is a `hidden beast` number, since 210 + 0 + 6 + 8 + 3 + 438 + 1 = 666.

It is not a de Polignac number, because 21006834381 - 2⁷ = 21006834253 is a prime.

It is a super-2 number, since 2×21006834381² (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 (21006834311) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 5920650 + ... + 5924196.

It is an arithmetic number, because the mean of its divisors is an integer number (536457600).

Almost surely, 2^21006834381 is an apocalyptic number.

It is an amenable number.

21006834381 is a deficient number, since it is larger than the sum of its proper divisors (13326452019).

21006834381 is a wasteful number, since it uses less digits than its factorization.

21006834381 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3975 (or 3969 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The spelling of 21006834381 in words is "twenty-one billion, six million, eight hundred thirty-four thousand, three hundred eighty-one".