21042151 has 4 divisors (see below), whose sum is σ = 22660792. Its totient is φ = 19423512.

The previous prime is 21042127. The next prime is 21042157. The reversal of 21042151 is 15124012.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21042151 - 2⁹ = 21041639 is a prime.

It is a super-3 number, since 3×21042151³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21042157) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 809301 + ... + 809326.

It is an arithmetic number, because the mean of its divisors is an integer number (5665198).

Almost surely, 2^21042151 is an apocalyptic number.

21042151 is a deficient number, since it is larger than the sum of its proper divisors (1618641).

21042151 is a wasteful number, since it uses less digits than its factorization.

21042151 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1618640.

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 21042151 is about 4587.1724406218. The cubic root of 21042151 is about 276.0768838179.

Adding to 21042151 its reverse (15124012), we get a palindrome (36166163).

The spelling of 21042151 in words is "twenty-one million, forty-two thousand, one hundred fifty-one".