21405383977 has 2 divisors, whose sum is σ = 21405383978. Its totient is φ = 21405383976.

The previous prime is 21405383971. The next prime is 21405384103. The reversal of 21405383977 is 77938350412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21344917801 + 60466176 = 146099^2 + 7776^2 .

It is a cyclic number.

It is not a de Polignac number, because 21405383977 - 2¹¹ = 21405381929 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21405383977.

It is not a weakly prime, because it can be changed into another prime (21405383971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10702691988 + 10702691989.

It is an arithmetic number, because the mean of its divisors is an integer number (10702691989).

Almost surely, 2^21405383977 is an apocalyptic number.

It is an amenable number.

21405383977 is a deficient number, since it is larger than the sum of its proper divisors (1).

21405383977 is an equidigital number, since it uses as much as digits as its factorization.

21405383977 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1270080, while the sum is 49.

The spelling of 21405383977 in words is "twenty-one billion, four hundred five million, three hundred eighty-three thousand, nine hundred seventy-seven".