21555434 has 4 divisors (see below), whose sum is σ = 32333154. Its totient is φ = 10777716.

The previous prime is 21555433. The next prime is 21555449. The reversal of 21555434 is 43455512.

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., 15626209 + 5929225 = 3953^2 + 2435^2 .

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21555397 and 21555406.

It is not an unprimeable number, because it can be changed into a prime (21555433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5388857 + ... + 5388860.

Almost surely, 2^21555434 is an apocalyptic number.

21555434 is a deficient number, since it is larger than the sum of its proper divisors (10777720).

21555434 is a wasteful number, since it uses less digits than its factorization.

21555434 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10777719.

The product of its digits is 12000, while the sum is 29.

The square root of 21555434 is about 4642.7830016058. The cubic root of 21555434 is about 278.3036638348.

The spelling of 21555434 in words is "twenty-one million, five hundred fifty-five thousand, four hundred thirty-four".