21620545470401 has 2 divisors, whose sum is σ = 21620545470402. Its totient is φ = 21620545470400.

The previous prime is 21620545470397. The next prime is 21620545470413. The reversal of 21620545470401 is 10407454502612.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20077792680625 + 1542752789776 = 4480825^2 + 1242076^2 .

It is a cyclic number.

It is not a de Polignac number, because 21620545470401 - 2² = 21620545470397 is a prime.

It is not a weakly prime, because it can be changed into another prime (21620545470431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10810272735200 + 10810272735201.

It is an arithmetic number, because the mean of its divisors is an integer number (10810272735201).

Almost surely, 2^{21620545470401} is an apocalyptic number.

It is an amenable number.

21620545470401 is a deficient number, since it is larger than the sum of its proper divisors (1).

21620545470401 is an equidigital number, since it uses as much as digits as its factorization.

21620545470401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 268800, while the sum is 41.

The spelling of 21620545470401 in words is "twenty-one trillion, six hundred twenty billion, five hundred forty-five million, four hundred seventy thousand, four hundred one".