21678201 has 6 divisors (see below), whose sum is σ = 31312970. Its totient is φ = 14452128.

The previous prime is 21678197. The next prime is 21678203. The reversal of 21678201 is 10287612.

It can be written as a sum of positive squares in only one way, i.e., 16160400 + 5517801 = 4020^2 + 2349^2 .

It is not a de Polignac number, because 21678201 - 2² = 21678197 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21678203) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1204336 + ... + 1204353.

Almost surely, 2^21678201 is an apocalyptic number.

It is an amenable number.

21678201 is a deficient number, since it is larger than the sum of its proper divisors (9634769).

21678201 is a wasteful number, since it uses less digits than its factorization.

21678201 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2408695 (or 2408692 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21678201 is about 4655.9855025547. The cubic root of 21678201 is about 278.8310149471.

The spelling of 21678201 in words is "twenty-one million, six hundred seventy-eight thousand, two hundred one".