21132457 has 4 divisors (see below), whose sum is σ = 21153616. Its totient is φ = 21111300.

The previous prime is 21132383. The next prime is 21132481. The reversal of 21132457 is 75423112.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21132457 - 2¹¹ = 21130409 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21132487) 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, 9003 + ... + 11104.

It is an arithmetic number, because the mean of its divisors is an integer number (5288404).

Almost surely, 2^21132457 is an apocalyptic number.

It is an amenable number.

21132457 is a deficient number, since it is larger than the sum of its proper divisors (21159).

21132457 is a wasteful number, since it uses less digits than its factorization.

21132457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21158.

The product of its digits is 1680, while the sum is 25.

The square root of 21132457 is about 4597.0052207932. The cubic root of 21132457 is about 276.4712639373.

Adding to 21132457 its reverse (75423112), we get a palindrome (96555569).

The spelling of 21132457 in words is "twenty-one million, one hundred thirty-two thousand, four hundred fifty-seven".