21961942769 has 4 divisors (see below), whose sum is σ = 23651322996. Its totient is φ = 20272562544.

The previous prime is 21961942747. The next prime is 21961942799. The reversal of 21961942769 is 96724916912.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2512014400 + 19449928369 = 50120^2 + 139463^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21961942769 is a prime.

It is a super-2 number, since 2×21961942769² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21961942799) 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, 844690094 + ... + 844690119.

It is an arithmetic number, because the mean of its divisors is an integer number (5912830749).

Almost surely, 2^21961942769 is an apocalyptic number.

It is an amenable number.

21961942769 is a deficient number, since it is larger than the sum of its proper divisors (1689380227).

21961942769 is a wasteful number, since it uses less digits than its factorization.

21961942769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1689380226.

The product of its digits is 2939328, while the sum is 56.

The spelling of 21961942769 in words is "twenty-one billion, nine hundred sixty-one million, nine hundred forty-two thousand, seven hundred sixty-nine".