21681586009801 has 9 divisors (see below), whose sum is σ = 22882875283053. Its totient is φ = 20540366089740.

The previous prime is 21681586009691. The next prime is 21681586009861. The reversal of 21681586009801 is 10890068518612.

The square root of 21681586009801 is 4656349.

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

It is not a de Polignac number, because 21681586009801 - 2¹³ = 21681586001609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21681586009861) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 88348096 + ... + 88593166.

It is an arithmetic number, because the mean of its divisors is an integer number (2542541698117).

Almost surely, 2^{21681586009801} is an apocalyptic number.

21681586009801 is the 4656349-th square number.

21681586009801 is the 2328175-th centered octagonal number.

It is an amenable number.

21681586009801 is a deficient number, since it is larger than the sum of its proper divisors (1201289273252).

21681586009801 is an frugal number, since it uses more digits than its factorization.

21681586009801 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 490180 (or 245090 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 55.

The spelling of 21681586009801 in words is "twenty-one trillion, six hundred eighty-one billion, five hundred eighty-six million, nine thousand, eight hundred one".