21651002 has 4 divisors (see below), whose sum is σ = 32476506. Its totient is φ = 10825500.

The previous prime is 21650999. The next prime is 21651011. The reversal of 21651002 is 20015612.

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

It can be written as a sum of positive squares in only one way, i.e., 20349121 + 1301881 = 4511^2 + 1141^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5412749 + ... + 5412752.

Almost surely, 2^21651002 is an apocalyptic number.

21651002 is a deficient number, since it is larger than the sum of its proper divisors (10825504).

21651002 is a wasteful number, since it uses less digits than its factorization.

21651002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10825503.

The product of its (nonzero) digits is 120, while the sum is 17.

The square root of 21651002 is about 4653.0637218934. The cubic root of 21651002 is about 278.7143524565.

Adding to 21651002 its reverse (20015612), we get a palindrome (41666614).

The spelling of 21651002 in words is "twenty-one million, six hundred fifty-one thousand, two".