21229638 has 16 divisors (see below), whose sum is σ = 43607280. Its totient is φ = 6885216.

The previous prime is 21229633. The next prime is 21229643. The reversal of 21229638 is 83692212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21229633) and next prime (21229643).

It is a super-2 number, since 2×21229638² = 901395059222088, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21229599 and 21229608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21229633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47593 + ... + 48036.

It is an arithmetic number, because the mean of its divisors is an integer number (2725455).

Almost surely, 2^21229638 is an apocalyptic number.

21229638 is an abundant number, since it is smaller than the sum of its proper divisors (22377642).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21229638 is a wasteful number, since it uses less digits than its factorization.

21229638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95671.

The product of its digits is 10368, while the sum is 33.

The square root of 21229638 is about 4607.5631303326. The cubic root of 21229638 is about 276.8944151366.

The spelling of 21229638 in words is "twenty-one million, two hundred twenty-nine thousand, six hundred thirty-eight".