21554610630991 has 2 divisors, whose sum is σ = 21554610630992. Its totient is φ = 21554610630990.

The previous prime is 21554610630947. The next prime is 21554610631061. The reversal of 21554610630991 is 19903601645512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21554610630991 - 2³¹ = 21552463147343 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21554610630191) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777305315495 + 10777305315496.

It is an arithmetic number, because the mean of its divisors is an integer number (10777305315496).

Almost surely, 2^{21554610630991} is an apocalyptic number.

21554610630991 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554610630991 is an equidigital number, since it uses as much as digits as its factorization.

21554610630991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1749600, while the sum is 52.

The spelling of 21554610630991 in words is "twenty-one trillion, five hundred fifty-four billion, six hundred ten million, six hundred thirty thousand, nine hundred ninety-one".