21147874779 has 32 divisors (see below), whose sum is σ = 30723112960. Its totient is φ = 12890080800.

The previous prime is 21147874777. The next prime is 21147874789. The reversal of 21147874779 is 97747874112.

It is a happy number.

It is not a de Polignac number, because 21147874779 - 2¹ = 21147874777 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (57).

It is not an unprimeable number, because it can be changed into a prime (21147874777) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 632184 + ... + 664794.

It is an arithmetic number, because the mean of its divisors is an integer number (960097280).

Almost surely, 2^21147874779 is an apocalyptic number.

21147874779 is a deficient number, since it is larger than the sum of its proper divisors (9575238181).

21147874779 is a wasteful number, since it uses less digits than its factorization.

21147874779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33031.

The product of its digits is 5531904, while the sum is 57.

The spelling of 21147874779 in words is "twenty-one billion, one hundred forty-seven million, eight hundred seventy-four thousand, seven hundred seventy-nine".