21308554 has 8 divisors (see below), whose sum is σ = 32400900. Its totient is φ = 10508256.

The previous prime is 21308543. The next prime is 21308579. The reversal of 21308554 is 45580312.

It can be written as a sum of positive squares in 2 ways, for example, as 17867529 + 3441025 = 4227^2 + 1855^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 72829 + ... + 73120.

Almost surely, 2^21308554 is an apocalyptic number.

21308554 is a deficient number, since it is larger than the sum of its proper divisors (11092346).

21308554 is a wasteful number, since it uses less digits than its factorization.

21308554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146024.

The product of its (nonzero) digits is 4800, while the sum is 28.

The square root of 21308554 is about 4616.1189326099. The cubic root of 21308554 is about 277.2370866994.

Adding to 21308554 its reverse (45580312), we get a palindrome (66888866).

The spelling of 21308554 in words is "twenty-one million, three hundred eight thousand, five hundred fifty-four".