21354554640421 has 2 divisors, whose sum is σ = 21354554640422. Its totient is φ = 21354554640420.

The previous prime is 21354554640413. The next prime is 21354554640479. The reversal of 21354554640421 is 12404645545312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13839225852321 + 7515328788100 = 3720111^2 + 2741410^2 .

It is a cyclic number.

It is not a de Polignac number, because 21354554640421 - 2³ = 21354554640413 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21354554640401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10677277320210 + 10677277320211.

It is an arithmetic number, because the mean of its divisors is an integer number (10677277320211).

Almost surely, 2^{21354554640421} is an apocalyptic number.

It is an amenable number.

21354554640421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21354554640421 is an equidigital number, since it uses as much as digits as its factorization.

21354554640421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304000, while the sum is 46.

The spelling of 21354554640421 in words is "twenty-one trillion, three hundred fifty-four billion, five hundred fifty-four million, six hundred forty thousand, four hundred twenty-one".