21696901 has 4 divisors (see below), whose sum is σ = 22445100. Its totient is φ = 20948704.

The previous prime is 21696877. The next prime is 21696923. The reversal of 21696901 is 10969612.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8844676 + 12852225 = 2974^2 + 3585^2 .

It is a cyclic number.

It is not a de Polignac number, because 21696901 - 2¹¹ = 21694853 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21696991) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 374056 + ... + 374113.

It is an arithmetic number, because the mean of its divisors is an integer number (5611275).

Almost surely, 2^21696901 is an apocalyptic number.

It is an amenable number.

21696901 is a deficient number, since it is larger than the sum of its proper divisors (748199).

21696901 is an equidigital number, since it uses as much as digits as its factorization.

21696901 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 748198.

The product of its (nonzero) digits is 5832, while the sum is 34.

The square root of 21696901 is about 4657.9932374361. The cubic root of 21696901 is about 278.9111667615.

The spelling of 21696901 in words is "twenty-one million, six hundred ninety-six thousand, nine hundred one".