21161372807 has 16 divisors (see below), whose sum is σ = 21841425408. Its totient is φ = 20490200640.

The previous prime is 21161372783. The next prime is 21161372809. The reversal of 21161372807 is 70827316112.

It is a cyclic number.

It is not a de Polignac number, because 21161372807 - 2²² = 21157178503 is a prime.

It is a Smith number, since the sum of its digits (38) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161372809) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 9873578 + ... + 9875720.

It is an arithmetic number, because the mean of its divisors is an integer number (1365089088).

Almost surely, 2^21161372807 is an apocalyptic number.

21161372807 is a deficient number, since it is larger than the sum of its proper divisors (680052601).

21161372807 is a wasteful number, since it uses less digits than its factorization.

21161372807 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4070.

The product of its (nonzero) digits is 28224, while the sum is 38.

Adding to 21161372807 its reverse (70827316112), we get a palindrome (91988688919).

The spelling of 21161372807 in words is "twenty-one billion, one hundred sixty-one million, three hundred seventy-two thousand, eight hundred seven".