21002042 has 8 divisors (see below), whose sum is σ = 31857300. Its totient is φ = 10382944.

The previous prime is 21002039. The next prime is 21002077. The reversal of 21002042 is 24020012.

It can be written as a sum of positive squares in 2 ways, for example, as 19704721 + 1297321 = 4439^2 + 1139^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 58817 + ... + 59172.

Almost surely, 2^21002042 is an apocalyptic number.

21002042 is a deficient number, since it is larger than the sum of its proper divisors (10855258).

21002042 is a wasteful number, since it uses less digits than its factorization.

21002042 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118080.

The product of its (nonzero) digits is 32, while the sum is 11.

The square root of 21002042 is about 4582.7984900059. The cubic root of 21002042 is about 275.9013597660.

Adding to 21002042 its reverse (24020012), we get a palindrome (45022054).

The spelling of 21002042 in words is "twenty-one million, two thousand, forty-two".