20401000643 has 2 divisors, whose sum is σ = 20401000644. Its totient is φ = 20401000642.

The previous prime is 20401000639. The next prime is 20401000657. The reversal of 20401000643 is 34600010402.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 20401000643 - 2² = 20401000639 is a prime.

It is not a weakly prime, because it can be changed into another prime (20401000693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200500321 + 10200500322.

It is an arithmetic number, because the mean of its divisors is an integer number (10200500322).

Almost surely, 2^20401000643 is an apocalyptic number.

20401000643 is a deficient number, since it is larger than the sum of its proper divisors (1).

20401000643 is an equidigital number, since it uses as much as digits as its factorization.

20401000643 is an odious number, because the sum of its binary digits is odd.

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

The spelling of 20401000643 in words is "twenty billion, four hundred one million, six hundred forty-three", and thus it is an aban number.