21040394 has 8 divisors (see below), whose sum is σ = 31663008. Its totient is φ = 10486060.

The previous prime is 21040387. The next prime is 21040427. The reversal of 21040394 is 49304012.

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, 16292 + ... + 17535.

It is an arithmetic number, because the mean of its divisors is an integer number (3957876).

Almost surely, 2^21040394 is an apocalyptic number.

21040394 is a deficient number, since it is larger than the sum of its proper divisors (10622614).

21040394 is a wasteful number, since it uses less digits than its factorization.

21040394 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34140.

The product of its (nonzero) digits is 864, while the sum is 23.

The square root of 21040394 is about 4586.9809243118. The cubic root of 21040394 is about 276.0691995498.

It can be divided in two parts, 210 and 40394, that added together give a palindrome (40604).

The spelling of 21040394 in words is "twenty-one million, forty thousand, three hundred ninety-four".