21755554 has 4 divisors (see below), whose sum is σ = 32633334. Its totient is φ = 10877776.

The previous prime is 21755527. The next prime is 21755579. The reversal of 21755554 is 45555712.

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., 11662225 + 10093329 = 3415^2 + 3177^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5438887 + ... + 5438890.

Almost surely, 2^21755554 is an apocalyptic number.

21755554 is a deficient number, since it is larger than the sum of its proper divisors (10877780).

21755554 is a wasteful number, since it uses less digits than its factorization.

21755554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10877779.

The product of its digits is 35000, while the sum is 34.

The square root of 21755554 is about 4664.2849398380. The cubic root of 21755554 is about 279.1622664884.

The spelling of 21755554 in words is "twenty-one million, seven hundred fifty-five thousand, five hundred fifty-four".