21122561779 has 16 divisors (see below), whose sum is σ = 23198822496. Its totient is φ = 19072748800.

The previous prime is 21122561777. The next prime is 21122561807. The reversal of 21122561779 is 97716522112.

It is not a de Polignac number, because 21122561779 - 2¹ = 21122561777 is a prime.

It is a super-2 number, since 2×21122561779² (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 (21122561777) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 969069 + ... + 990625.

It is an arithmetic number, because the mean of its divisors is an integer number (1449926406).

Almost surely, 2^21122561779 is an apocalyptic number.

21122561779 is a deficient number, since it is larger than the sum of its proper divisors (2076260717).

21122561779 is a wasteful number, since it uses less digits than its factorization.

21122561779 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22166.

The product of its digits is 105840, while the sum is 43.

The spelling of 21122561779 in words is "twenty-one billion, one hundred twenty-two million, five hundred sixty-one thousand, seven hundred seventy-nine".