21520154 has 8 divisors (see below), whose sum is σ = 32334240. Its totient is φ = 10742076.

The previous prime is 21520151. The next prime is 21520159. The reversal of 21520154 is 45102512.

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

It is not an unprimeable number, because it can be changed into a prime (21520151) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7454 + ... + 9929.

It is an arithmetic number, because the mean of its divisors is an integer number (4041780).

Almost surely, 2^21520154 is an apocalyptic number.

21520154 is a deficient number, since it is larger than the sum of its proper divisors (10814086).

21520154 is a wasteful number, since it uses less digits than its factorization.

21520154 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18004.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 21520154 is about 4638.9820003962. The cubic root of 21520154 is about 278.1517467691.

Adding to 21520154 its reverse (45102512), we get a palindrome (66622666).

The spelling of 21520154 in words is "twenty-one million, five hundred twenty thousand, one hundred fifty-four".