21101554 has 4 divisors (see below), whose sum is σ = 31652334. Its totient is φ = 10550776.

The previous prime is 21101551. The next prime is 21101569. The reversal of 21101554 is 45510112.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 20912329 + 189225 = 4573^2 + 435^2 .

It is not an unprimeable number, because it can be changed into a prime (21101551) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5275387 + ... + 5275390.

Almost surely, 2^21101554 is an apocalyptic number.

21101554 is a deficient number, since it is larger than the sum of its proper divisors (10550780).

21101554 is a wasteful number, since it uses less digits than its factorization.

21101554 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10550779.

The product of its (nonzero) digits is 200, while the sum is 19.

The square root of 21101554 is about 4593.6427810617. The cubic root of 21101554 is about 276.3364324863.

Adding to 21101554 its reverse (45510112), we get a palindrome (66611666).

The spelling of 21101554 in words is "twenty-one million, one hundred one thousand, five hundred fifty-four".