21369811 has 2 divisors, whose sum is σ = 21369812. Its totient is φ = 21369810.

The previous prime is 21369797. The next prime is 21369847. The reversal of 21369811 is 11896312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21369811 - 2¹¹ = 21367763 is a prime.

It is not a weakly prime, because it can be changed into another prime (21369871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10684905 + 10684906.

It is an arithmetic number, because the mean of its divisors is an integer number (10684906).

Almost surely, 2^21369811 is an apocalyptic number.

21369811 is a deficient number, since it is larger than the sum of its proper divisors (1).

21369811 is an equidigital number, since it uses as much as digits as its factorization.

21369811 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2592, while the sum is 31.

The square root of 21369811 is about 4622.7492901952. The cubic root of 21369811 is about 277.5024959871.

The spelling of 21369811 in words is "twenty-one million, three hundred sixty-nine thousand, eight hundred eleven".