21661054461503 has 4 divisors (see below), whose sum is σ = 21661995819288. Its totient is φ = 21660113103720.

The previous prime is 21661054461443. The next prime is 21661054461559. The reversal of 21661054461503 is 30516445016612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21661054461503 - 2⁶ = 21661054461439 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661054461203) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 470644376 + ... + 470690397.

It is an arithmetic number, because the mean of its divisors is an integer number (5415498954822).

Almost surely, 2^{21661054461503} is an apocalyptic number.

21661054461503 is a deficient number, since it is larger than the sum of its proper divisors (941357785).

21661054461503 is an equidigital number, since it uses as much as digits as its factorization.

21661054461503 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 941357784.

The product of its (nonzero) digits is 518400, while the sum is 44.

The spelling of 21661054461503 in words is "twenty-one trillion, six hundred sixty-one billion, fifty-four million, four hundred sixty-one thousand, five hundred three".