11421979681 has 4 divisors (see below), whose sum is σ = 13053691072. Its totient is φ = 9790268292.

The previous prime is 11421979633. The next prime is 11421979693. The reversal of 11421979681 is 18697912411.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18697912411 = 257 ⋅72754523.

It is not a de Polignac number, because 11421979681 - 2⁷ = 11421979553 is a prime.

It is a super-2 number, since 2×11421979681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (11421979381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 815855685 + ... + 815855698.

It is an arithmetic number, because the mean of its divisors is an integer number (3263422768).

Almost surely, 2^11421979681 is an apocalyptic number.

It is an amenable number.

11421979681 is a deficient number, since it is larger than the sum of its proper divisors (1631711391).

11421979681 is an equidigital number, since it uses as much as digits as its factorization.

11421979681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631711390.

The product of its digits is 217728, while the sum is 49.

The spelling of 11421979681 in words is "eleven billion, four hundred twenty-one million, nine hundred seventy-nine thousand, six hundred eighty-one".