21640996 has 24 divisors (see below), whose sum is σ = 41350904. Its totient is φ = 9849600.

The previous prime is 21640987. The next prime is 21641003. The reversal of 21640996 is 69904612.

It can be written as a sum of positive squares in 4 ways, for example, as 3663396 + 17977600 = 1914^2 + 4240^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 946 + ... + 6646.

Almost surely, 2^21640996 is an apocalyptic number.

21640996 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21640996 is a deficient number, since it is larger than the sum of its proper divisors (19709908).

21640996 is a wasteful number, since it uses less digits than its factorization.

21640996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5791 (or 5789 counting only the distinct ones).

The product of its (nonzero) digits is 23328, while the sum is 37.

The square root of 21640996 is about 4651.9883920749. The cubic root of 21640996 is about 278.6714099399.

The spelling of 21640996 in words is "twenty-one million, six hundred forty thousand, nine hundred ninety-six".