21075554 has 4 divisors (see below), whose sum is σ = 31613334. Its totient is φ = 10537776.

The previous prime is 21075497. The next prime is 21075559. The reversal of 21075554 is 45557012.

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., 11937025 + 9138529 = 3455^2 + 3023^2 .

It is not an unprimeable number, because it can be changed into a prime (21075559) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5268887 + ... + 5268890.

Almost surely, 2^21075554 is an apocalyptic number.

21075554 is a deficient number, since it is larger than the sum of its proper divisors (10537780).

21075554 is a wasteful number, since it uses less digits than its factorization.

21075554 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10537779.

The product of its (nonzero) digits is 7000, while the sum is 29.

The square root of 21075554 is about 4590.8119107626. The cubic root of 21075554 is about 276.2228910835. Note that the first 3 decimals are identical.

The spelling of 21075554 in words is "twenty-one million, seventy-five thousand, five hundred fifty-four".