21008292891 has 16 divisors (see below), whose sum is σ = 28117290240. Its totient is φ = 13952465120.

The previous prime is 21008292881. The next prime is 21008292917. The reversal of 21008292891 is 19829280012.

It is a cyclic number.

It is not a de Polignac number, because 21008292891 - 2⁹ = 21008292379 is a prime.

It is a super-2 number, since 2×21008292891² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21008292881) 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, 1924936 + ... + 1935818.

It is an arithmetic number, because the mean of its divisors is an integer number (1757330640).

Almost surely, 2^21008292891 is an apocalyptic number.

21008292891 is a deficient number, since it is larger than the sum of its proper divisors (7108997349).

21008292891 is a wasteful number, since it uses less digits than its factorization.

21008292891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13266.

The product of its (nonzero) digits is 41472, while the sum is 42.

The spelling of 21008292891 in words is "twenty-one billion, eight million, two hundred ninety-two thousand, eight hundred ninety-one".