21351042 has 12 divisors (see below), whose sum is σ = 46260630. Its totient is φ = 7117008.

The previous prime is 21351017. The next prime is 21351053. The reversal of 21351042 is 24015312.

It can be written as a sum of positive squares in only one way, i.e., 17969121 + 3381921 = 4239^2 + 1839^2 .

It is a Harshad number since it is a multiple of its sum of digits (18), and also a Moran number because the ratio is a prime number: 1186169 = 21351042 / (2 + 1 + 3 + 5 + 1 + 0 + 4 + 2).

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 593067 + ... + 593102.

Almost surely, 2^21351042 is an apocalyptic number.

21351042 is an abundant number, since it is smaller than the sum of its proper divisors (24909588).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21351042 is a wasteful number, since it uses less digits than its factorization.

21351042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1186177 (or 1186174 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21351042 is about 4620.7187752556. The cubic root of 21351042 is about 277.4212291641.

Adding to 21351042 its reverse (24015312), we get a palindrome (45366354).

The spelling of 21351042 in words is "twenty-one million, three hundred fifty-one thousand, forty-two".