21421769 has 2 divisors, whose sum is σ = 21421770. Its totient is φ = 21421768.

The previous prime is 21421747. The next prime is 21421793. The reversal of 21421769 is 96712412.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19891600 + 1530169 = 4460^2 + 1237^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21421769 is a prime.

It is a super-2 number, since 2×21421769² = 917784374178722, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21423769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10710884 + 10710885.

It is an arithmetic number, because the mean of its divisors is an integer number (10710885).

Almost surely, 2^21421769 is an apocalyptic number.

It is an amenable number.

21421769 is a deficient number, since it is larger than the sum of its proper divisors (1).

21421769 is an equidigital number, since it uses as much as digits as its factorization.

21421769 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6048, while the sum is 32.

The square root of 21421769 is about 4628.3656942813. The cubic root of 21421769 is about 277.7272180631.

The spelling of 21421769 in words is "twenty-one million, four hundred twenty-one thousand, seven hundred sixty-nine".