21154521 has 8 divisors (see below), whose sum is σ = 28603584. Its totient is φ = 13904240.

The previous prime is 21154519. The next prime is 21154547. The reversal of 21154521 is 12545112.

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 21154521 - 2¹ = 21154519 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21154591) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 49446 + ... + 49871.

It is an arithmetic number, because the mean of its divisors is an integer number (3575448).

Almost surely, 2^21154521 is an apocalyptic number.

It is an amenable number.

21154521 is a deficient number, since it is larger than the sum of its proper divisors (7449063).

21154521 is an equidigital number, since it uses as much as digits as its factorization.

21154521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99391.

The product of its digits is 400, while the sum is 21.

The square root of 21154521 is about 4599.4044179654. The cubic root of 21154521 is about 276.5674499481.

Adding to 21154521 its reverse (12545112), we get a palindrome (33699633).

The spelling of 21154521 in words is "twenty-one million, one hundred fifty-four thousand, five hundred twenty-one".