21051432 has 24 divisors (see below), whose sum is σ = 57014490. Its totient is φ = 7017120.

The previous prime is 21051431. The next prime is 21051451. The reversal of 21051432 is 23415012.

It can be written as a sum of positive squares in only one way, i.e., 13793796 + 7257636 = 3714^2 + 2694^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21051431) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 146119 + ... + 146262.

Almost surely, 2^21051432 is an apocalyptic number.

It is an amenable number.

21051432 is an abundant number, since it is smaller than the sum of its proper divisors (35963058).

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

21051432 is a wasteful number, since it uses less digits than its factorization.

21051432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 292393 (or 292386 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21051432 is about 4588.1839544639. The cubic root of 21051432 is about 276.1174673264.

Adding to 21051432 its reverse (23415012), we get a palindrome (44466444).

The spelling of 21051432 in words is "twenty-one million, fifty-one thousand, four hundred thirty-two".