21431601 has 16 divisors (see below), whose sum is σ = 33422400. Its totient is φ = 13535424.

The previous prime is 21431593. The next prime is 21431623. The reversal of 21431601 is 10613412.

It is a happy number.

21431601 is a `hidden beast` number, since 21 + 43 + 1 + 601 = 666.

It is not a de Polignac number, because 21431601 - 2³ = 21431593 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21431681) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 20376 + ... + 21401.

It is an arithmetic number, because the mean of its divisors is an integer number (2088900).

Almost surely, 2^21431601 is an apocalyptic number.

It is an amenable number.

21431601 is a deficient number, since it is larger than the sum of its proper divisors (11990799).

21431601 is a wasteful number, since it uses less digits than its factorization.

21431601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41805 (or 41799 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 18.

The square root of 21431601 is about 4629.4277184119. The cubic root of 21431601 is about 277.7697012704.

The spelling of 21431601 in words is "twenty-one million, four hundred thirty-one thousand, six hundred one".