21461891078 has 16 divisors (see below), whose sum is σ = 33744964176. Its totient is φ = 10225743360.

The previous prime is 21461891069. The next prime is 21461891117. The reversal of 21461891078 is 87019816412.

It is a super-2 number, since 2×21461891078² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3039851 + ... + 3046902.

It is an arithmetic number, because the mean of its divisors is an integer number (2109060261).

Almost surely, 2^21461891078 is an apocalyptic number.

21461891078 is a deficient number, since it is larger than the sum of its proper divisors (12283073098).

21461891078 is a wasteful number, since it uses less digits than its factorization.

21461891078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6086839.

The product of its (nonzero) digits is 193536, while the sum is 47.

The spelling of 21461891078 in words is "twenty-one billion, four hundred sixty-one million, eight hundred ninety-one thousand, seventy-eight".