21026377 has 2 divisors, whose sum is σ = 21026378. Its totient is φ = 21026376.

The previous prime is 21026371. The next prime is 21026381. The reversal of 21026377 is 77362012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20259001 + 767376 = 4501^2 + 876^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21026377 is a prime.

It is a super-2 number, since 2×21026377² = 884217059492258, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21026371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10513188 + 10513189.

It is an arithmetic number, because the mean of its divisors is an integer number (10513189).

Almost surely, 2^21026377 is an apocalyptic number.

It is an amenable number.

21026377 is a deficient number, since it is larger than the sum of its proper divisors (1).

21026377 is an equidigital number, since it uses as much as digits as its factorization.

21026377 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3528, while the sum is 28.

The square root of 21026377 is about 4585.4527584525. The cubic root of 21026377 is about 276.0078806473.

Adding to 21026377 its reverse (77362012), we get a palindrome (98388389).

The spelling of 21026377 in words is "twenty-one million, twenty-six thousand, three hundred seventy-seven".