20401643 has 4 divisors (see below), whose sum is σ = 20462520. Its totient is φ = 20340768.

The previous prime is 20401613. The next prime is 20401663. The reversal of 20401643 is 34610402.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20401643 - 2¹⁸ = 20139499 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20401603) 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, 29933 + ... + 30606.

It is an arithmetic number, because the mean of its divisors is an integer number (5115630).

Almost surely, 2^20401643 is an apocalyptic number.

20401643 is a deficient number, since it is larger than the sum of its proper divisors (60877).

20401643 is an equidigital number, since it uses as much as digits as its factorization.

20401643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 60876.

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 20401643 is about 4516.8177957496. The cubic root of 20401643 is about 273.2467769093.

The spelling of 20401643 in words is "twenty million, four hundred one thousand, six hundred forty-three".