21554509751 has 2 divisors, whose sum is σ = 21554509752. Its totient is φ = 21554509750.

The previous prime is 21554509733. The next prime is 21554509771. The reversal of 21554509751 is 15790545512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21554509751 - 2¹⁰ = 21554508727 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21554509721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10777254875 + 10777254876.

It is an arithmetic number, because the mean of its divisors is an integer number (10777254876).

Almost surely, 2^21554509751 is an apocalyptic number.

21554509751 is a deficient number, since it is larger than the sum of its proper divisors (1).

21554509751 is an equidigital number, since it uses as much as digits as its factorization.

21554509751 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 315000, while the sum is 44.

The spelling of 21554509751 in words is "twenty-one billion, five hundred fifty-four million, five hundred nine thousand, seven hundred fifty-one".