21366377 has 2 divisors, whose sum is σ = 21366378. Its totient is φ = 21366376.

The previous prime is 21366343. The next prime is 21366391. The reversal of 21366377 is 77366312.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19855936 + 1510441 = 4456^2 + 1229^2 .

It is a cyclic number.

It is not a de Polignac number, because 21366377 - 2¹⁰ = 21365353 is a prime.

It is a super-2 number, since 2×21366377² = 913044132212258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21366077) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10683188 + 10683189.

It is an arithmetic number, because the mean of its divisors is an integer number (10683189).

Almost surely, 2^21366377 is an apocalyptic number.

It is an amenable number.

21366377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21366377 is an equidigital number, since it uses as much as digits as its factorization.

21366377 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31752, while the sum is 35.

The square root of 21366377 is about 4622.3778512796. The cubic root of 21366377 is about 277.4876308639.

The spelling of 21366377 in words is "twenty-one million, three hundred sixty-six thousand, three hundred seventy-seven".