21253813378 has 16 divisors (see below), whose sum is σ = 36437218560. Its totient is φ = 9108249696.

The previous prime is 21253813363. The next prime is 21253813379. The reversal of 21253813378 is 87331835212.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21253813379) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 298375 + ... + 362677.

It is an arithmetic number, because the mean of its divisors is an integer number (2277326160).

Almost surely, 2^21253813378 is an apocalyptic number.

21253813378 is a deficient number, since it is larger than the sum of its proper divisors (15183405182).

21253813378 is a wasteful number, since it uses less digits than its factorization.

21253813378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 87921.

The product of its digits is 241920, while the sum is 43.

The spelling of 21253813378 in words is "twenty-one billion, two hundred fifty-three million, eight hundred thirteen thousand, three hundred seventy-eight".