20401010821 has 2 divisors, whose sum is σ = 20401010822. Its totient is φ = 20401010820.

The previous prime is 20401010801. The next prime is 20401010831. The reversal of 20401010821 is 12801010402.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11957422500 + 8443588321 = 109350^2 + 91889^2 .

It is a cyclic number.

It is not a de Polignac number, because 20401010821 - 2¹¹ = 20401008773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20401010801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10200505410 + 10200505411.

It is an arithmetic number, because the mean of its divisors is an integer number (10200505411).

Almost surely, 2^20401010821 is an apocalyptic number.

It is an amenable number.

20401010821 is a deficient number, since it is larger than the sum of its proper divisors (1).

20401010821 is an equidigital number, since it uses as much as digits as its factorization.

20401010821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

The spelling of 20401010821 in words is "twenty billion, four hundred one million, ten thousand, eight hundred twenty-one".