21609728784001 has 4 divisors (see below), whose sum is σ = 21609745463232. Its totient is φ = 21609712104772.

The previous prime is 21609728783971. The next prime is 21609728784031. The reversal of 21609728784001 is 10048782790612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21609728783971) and next prime (21609728784031).

It is a cyclic number.

It is not a de Polignac number, because 21609728784001 - 2³⁷ = 21472289830529 is a prime.

It is a super-2 number, since 2×21609728784001² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21609728784031) 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, 6215941 + ... + 9047506.

It is an arithmetic number, because the mean of its divisors is an integer number (5402436365808).

Almost surely, 2^{21609728784001} is an apocalyptic number.

It is an amenable number.

21609728784001 is a deficient number, since it is larger than the sum of its proper divisors (16679231).

21609728784001 is a wasteful number, since it uses less digits than its factorization.

21609728784001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16679230.

The product of its (nonzero) digits is 2709504, while the sum is 55.

The spelling of 21609728784001 in words is "twenty-one trillion, six hundred nine billion, seven hundred twenty-eight million, seven hundred eighty-four thousand, one".