21402044077 has 2 divisors, whose sum is σ = 21402044078. Its totient is φ = 21402044076.

The previous prime is 21402044057. The next prime is 21402044113. The reversal of 21402044077 is 77044020412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14616568201 + 6785475876 = 120899^2 + 82374^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21402044077 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21402044047) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701022038 + 10701022039.

It is an arithmetic number, because the mean of its divisors is an integer number (10701022039).

Almost surely, 2^21402044077 is an apocalyptic number.

It is an amenable number.

21402044077 is a deficient number, since it is larger than the sum of its proper divisors (1).

21402044077 is an equidigital number, since it uses as much as digits as its factorization.

21402044077 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12544, while the sum is 31.

Adding to 21402044077 its reverse (77044020412), we get a palindrome (98446064489).

The spelling of 21402044077 in words is "twenty-one billion, four hundred two million, forty-four thousand, seventy-seven".