21033554 has 4 divisors (see below), whose sum is σ = 31550334. Its totient is φ = 10516776.

The previous prime is 21033541. The next prime is 21033557. The reversal of 21033554 is 45533012.

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., 20043529 + 990025 = 4477^2 + 995^2 .

It is not an unprimeable number, because it can be changed into a prime (21033557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5258387 + ... + 5258390.

Almost surely, 2^21033554 is an apocalyptic number.

21033554 is a deficient number, since it is larger than the sum of its proper divisors (10516780).

21033554 is a wasteful number, since it uses less digits than its factorization.

21033554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10516779.

The product of its (nonzero) digits is 1800, while the sum is 23.

The square root of 21033554 is about 4586.2352752557. The cubic root of 21033554 is about 276.0392806237.

Adding to 21033554 its reverse (45533012), we get a palindrome (66566566).

The spelling of 21033554 in words is "twenty-one million, thirty-three thousand, five hundred fifty-four".