21170642 has 4 divisors (see below), whose sum is σ = 31755966. Its totient is φ = 10585320.

The previous prime is 21170641. The next prime is 21170647. The reversal of 21170642 is 24607112.

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., 20967241 + 203401 = 4579^2 + 451^2 .

It is not an unprimeable number, because it can be changed into a prime (21170641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5292659 + ... + 5292662.

Almost surely, 2^21170642 is an apocalyptic number.

21170642 is a deficient number, since it is larger than the sum of its proper divisors (10585324).

21170642 is a wasteful number, since it uses less digits than its factorization.

21170642 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10585323.

The product of its (nonzero) digits is 672, while the sum is 23.

The square root of 21170642 is about 4601.1565937273. The cubic root of 21170642 is about 276.6376857113.

Adding to 21170642 its reverse (24607112), we get a palindrome (45777754).

It can be divided in two parts, 21170 and 642, that added together give a palindrome (21812).

The spelling of 21170642 in words is "twenty-one million, one hundred seventy thousand, six hundred forty-two".