21820152 has 16 divisors (see below), whose sum is σ = 54550440. Its totient is φ = 7273376.

The previous prime is 21820133. The next prime is 21820157. The reversal of 21820152 is 25102812.

It is a happy number.

It is a super-2 number, since 2×21820152² = 952238066606208, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21820157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 454563 + ... + 454610.

Almost surely, 2^21820152 is an apocalyptic number.

It is an amenable number.

21820152 is an abundant number, since it is smaller than the sum of its proper divisors (32730288).

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

21820152 is a wasteful number, since it uses less digits than its factorization.

21820152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 909182 (or 909178 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 21.

The square root of 21820152 is about 4671.2045555724. The cubic root of 21820152 is about 279.4382956946.

Adding to 21820152 its reverse (25102812), we get a palindrome (46922964).

The spelling of 21820152 in words is "twenty-one million, eight hundred twenty thousand, one hundred fifty-two".