21464640778 has 16 divisors (see below), whose sum is σ = 36799545024. Its totient is φ = 9198377280.

The previous prime is 21464640767. The next prime is 21464640781. The reversal of 21464640778 is 87704646412.

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, 135501 + ... + 247567.

It is an arithmetic number, because the mean of its divisors is an integer number (2299971564).

Almost surely, 2^21464640778 is an apocalyptic number.

21464640778 is a deficient number, since it is larger than the sum of its proper divisors (15334904246).

21464640778 is a wasteful number, since it uses less digits than its factorization.

21464640778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 125757.

The product of its (nonzero) digits is 1806336, while the sum is 49.

The spelling of 21464640778 in words is "twenty-one billion, four hundred sixty-four million, six hundred forty thousand, seven hundred seventy-eight".