21394777 has 2 divisors, whose sum is σ = 21394778. Its totient is φ = 21394776.

The previous prime is 21394771. The next prime is 21394781. The reversal of 21394777 is 77749312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17799961 + 3594816 = 4219^2 + 1896^2 .

It is a cyclic number.

It is not a de Polignac number, because 21394777 - 2¹¹ = 21392729 is a prime.

It is not a weakly prime, because it can be changed into another prime (21394771) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10697388 + 10697389.

It is an arithmetic number, because the mean of its divisors is an integer number (10697389).

Almost surely, 2^21394777 is an apocalyptic number.

It is an amenable number.

21394777 is a deficient number, since it is larger than the sum of its proper divisors (1).

21394777 is an equidigital number, since it uses as much as digits as its factorization.

21394777 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 74088, while the sum is 40.

The square root of 21394777 is about 4625.4488430854. The cubic root of 21394777 is about 277.6105211362.

The spelling of 21394777 in words is "twenty-one million, three hundred ninety-four thousand, seven hundred seventy-seven".