21534457 has 8 divisors (see below), whose sum is σ = 24651200. Its totient is φ = 18427824.

The previous prime is 21534451. The next prime is 21534479. The reversal of 21534457 is 75443512.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21534457 - 2⁷ = 21534329 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21534451) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2794 + ... + 7132.

It is an arithmetic number, because the mean of its divisors is an integer number (3081400).

Almost surely, 2^21534457 is an apocalyptic number.

It is an amenable number.

21534457 is a deficient number, since it is larger than the sum of its proper divisors (3116743).

21534457 is an equidigital number, since it uses as much as digits as its factorization.

21534457 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5055.

The product of its digits is 16800, while the sum is 31.

The square root of 21534457 is about 4640.5233541057. The cubic root of 21534457 is about 278.2133560458.

Adding to 21534457 its reverse (75443512), we get a palindrome (96977969).

The spelling of 21534457 in words is "twenty-one million, five hundred thirty-four thousand, four hundred fifty-seven".