21154557 has 8 divisors (see below), whose sum is σ = 28254976. Its totient is φ = 14078592.

The previous prime is 21154547. The next prime is 21154577. The reversal of 21154557 is 75545112.

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

It is not a de Polignac number, because 21154557 - 2¹⁰ = 21153533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21154547) 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, 3988 + ... + 7629.

It is an arithmetic number, because the mean of its divisors is an integer number (3531872).

Almost surely, 2^21154557 is an apocalyptic number.

It is an amenable number.

21154557 is a deficient number, since it is larger than the sum of its proper divisors (7100419).

21154557 is a wasteful number, since it uses less digits than its factorization.

21154557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12227.

The product of its digits is 7000, while the sum is 30.

The square root of 21154557 is about 4599.4083315140. The cubic root of 21154557 is about 276.5676068322.

Adding to 21154557 its reverse (75545112), we get a palindrome (96699669).

The spelling of 21154557 in words is "twenty-one million, one hundred fifty-four thousand, five hundred fifty-seven".