21949638 has 16 divisors (see below), whose sum is σ = 43945200. Its totient is φ = 7308896.

The previous prime is 21949633. The next prime is 21949639. The reversal of 21949638 is 83694912.

It is a self number, because there is not a number n which added to its sum of digits gives 21949638.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21949633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10288 + ... + 12236.

It is an arithmetic number, because the mean of its divisors is an integer number (2746575).

Almost surely, 2^21949638 is an apocalyptic number.

21949638 is an abundant number, since it is smaller than the sum of its proper divisors (21995562).

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

21949638 is a wasteful number, since it uses less digits than its factorization.

21949638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3831.

The product of its digits is 93312, while the sum is 42.

The square root of 21949638 is about 4685.0440766336. The cubic root of 21949638 is about 279.9899571228.

The spelling of 21949638 in words is "twenty-one million, nine hundred forty-nine thousand, six hundred thirty-eight".