21640353 has 8 divisors (see below), whose sum is σ = 32975808. Its totient is φ = 12365904.

The previous prime is 21640331. The next prime is 21640357. The reversal of 21640353 is 35304612.

It is a happy number.

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

It is not a de Polignac number, because 21640353 - 2¹⁰ = 21639329 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21640357) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 515226 + ... + 515267.

It is an arithmetic number, because the mean of its divisors is an integer number (4121976).

Almost surely, 2^21640353 is an apocalyptic number.

It is an amenable number.

21640353 is a deficient number, since it is larger than the sum of its proper divisors (11335455).

21640353 is a wasteful number, since it uses less digits than its factorization.

21640353 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1030503.

The product of its (nonzero) digits is 2160, while the sum is 24.

The square root of 21640353 is about 4651.9192813289. The cubic root of 21640353 is about 278.6686499392.

Adding to 21640353 its reverse (35304612), we get a palindrome (56944965).

The spelling of 21640353 in words is "twenty-one million, six hundred forty thousand, three hundred fifty-three".