21154968377 has 2 divisors, whose sum is σ = 21154968378. Its totient is φ = 21154968376.

The previous prime is 21154968347. The next prime is 21154968431. The reversal of 21154968377 is 77386945112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20683904761 + 471063616 = 143819^2 + 21704^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154968377 - 2²⁴ = 21138191161 is a prime.

It is not a weakly prime, because it can be changed into another prime (21154968347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577484188 + 10577484189.

It is an arithmetic number, because the mean of its divisors is an integer number (10577484189).

Almost surely, 2^21154968377 is an apocalyptic number.

It is an amenable number.

21154968377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154968377 is an equidigital number, since it uses as much as digits as its factorization.

21154968377 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2540160, while the sum is 53.

The spelling of 21154968377 in words is "twenty-one billion, one hundred fifty-four million, nine hundred sixty-eight thousand, three hundred seventy-seven".