21186769 has 2 divisors, whose sum is σ = 21186770. Its totient is φ = 21186768.

The previous prime is 21186701. The next prime is 21186793. The reversal of 21186769 is 96768112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15484225 + 5702544 = 3935^2 + 2388^2 .

It is a cyclic number.

It is not a de Polignac number, because 21186769 - 2²¹ = 19089617 is a prime.

It is a super-2 number, since 2×21186769² = 897758361318722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21186799) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10593384 + 10593385.

It is an arithmetic number, because the mean of its divisors is an integer number (10593385).

Almost surely, 2^21186769 is an apocalyptic number.

It is an amenable number.

21186769 is a deficient number, since it is larger than the sum of its proper divisors (1).

21186769 is an equidigital number, since it uses as much as digits as its factorization.

21186769 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 40.

The square root of 21186769 is about 4602.9087542553. The cubic root of 21186769 is about 276.7079119490.

The spelling of 21186769 in words is "twenty-one million, one hundred eighty-six thousand, seven hundred sixty-nine".