21387152 has 20 divisors (see below), whose sum is σ = 42867420. Its totient is φ = 10324608.

The previous prime is 21387151. The next prime is 21387161. The reversal of 21387152 is 25178312.

It can be written as a sum of positive squares in 2 ways, for example, as 10863616 + 10523536 = 3296^2 + 3244^2 .

It is a super-2 number, since 2×21387152² = 914820541342208, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is not an unprimeable number, because it can be changed into a prime (21387151) 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 3 ways as a sum of consecutive naturals, for example, 22583 + ... + 23510.

It is an arithmetic number, because the mean of its divisors is an integer number (2143371).

Almost surely, 2^21387152 is an apocalyptic number.

It is an amenable number.

21387152 is an abundant number, since it is smaller than the sum of its proper divisors (21480268).

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

21387152 is a wasteful number, since it uses less digits than its factorization.

21387152 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46130 (or 46124 counting only the distinct ones).

The product of its digits is 3360, while the sum is 29.

The square root of 21387152 is about 4624.6245252993. The cubic root of 21387152 is about 277.5775375137.

The spelling of 21387152 in words is "twenty-one million, three hundred eighty-seven thousand, one hundred fifty-two".