21000642 has 32 divisors (see below), whose sum is σ = 45431232. Its totient is φ = 6433344.

The previous prime is 21000613. The next prime is 21000673. The reversal of 21000642 is 24600012.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23508 + ... + 24384.

It is an arithmetic number, because the mean of its divisors is an integer number (1419726).

Almost surely, 2^21000642 is an apocalyptic number.

21000642 is an abundant number, since it is smaller than the sum of its proper divisors (24430590).

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

21000642 is a wasteful number, since it uses less digits than its factorization.

21000642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1202.

The product of its (nonzero) digits is 96, while the sum is 15.

The square root of 21000642 is about 4582.6457423632. The cubic root of 21000642 is about 275.8952290846.

Adding to 21000642 its reverse (24600012), we get a palindrome (45600654).

The spelling of 21000642 in words is "twenty-one million, six hundred forty-two", and thus it is an aban number.