21749029 has 2 divisors, whose sum is σ = 21749030. Its totient is φ = 21749028.

The previous prime is 21749023. The next prime is 21749051. The reversal of 21749029 is 92094712.

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., 20702500 + 1046529 = 4550^2 + 1023^2 .

It is a cyclic number.

It is not a de Polignac number, because 21749029 - 2¹¹ = 21746981 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21748985 and 21749003.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21749023) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10874514 + 10874515.

It is an arithmetic number, because the mean of its divisors is an integer number (10874515).

Almost surely, 2^21749029 is an apocalyptic number.

It is an amenable number.

21749029 is a deficient number, since it is larger than the sum of its proper divisors (1).

21749029 is an equidigital number, since it uses as much as digits as its factorization.

21749029 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 34.

The square root of 21749029 is about 4663.5854232554. The cubic root of 21749029 is about 279.1343545979.

The spelling of 21749029 in words is "twenty-one million, seven hundred forty-nine thousand, twenty-nine".