21624349 has 2 divisors, whose sum is σ = 21624350. Its totient is φ = 21624348.

The previous prime is 21624331. The next prime is 21624353. The reversal of 21624349 is 94342612.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21622500 + 1849 = 4650^2 + 43^2 .

It is a cyclic number.

It is not a de Polignac number, because 21624349 - 2¹¹ = 21622301 is a prime.

It is a super-2 number, since 2×21624349² = 935224939347602, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21624349.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21624359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10812174 + 10812175.

It is an arithmetic number, because the mean of its divisors is an integer number (10812175).

Almost surely, 2^21624349 is an apocalyptic number.

It is an amenable number.

21624349 is a deficient number, since it is larger than the sum of its proper divisors (1).

21624349 is an equidigital number, since it uses as much as digits as its factorization.

21624349 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10368, while the sum is 31.

The square root of 21624349 is about 4650.1988129541. The cubic root of 21624349 is about 278.5999370592.

The spelling of 21624349 in words is "twenty-one million, six hundred twenty-four thousand, three hundred forty-nine".