21961318145 has 16 divisors (see below), whose sum is σ = 28386204672. Its totient is φ = 16214489280.

The previous prime is 21961318139. The next prime is 21961318201. The reversal of 21961318145 is 54181316912.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-21961318145 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 343880 + ... + 402710.

It is an arithmetic number, because the mean of its divisors is an integer number (1774137792).

Almost surely, 2^21961318145 is an apocalyptic number.

It is an amenable number.

21961318145 is a deficient number, since it is larger than the sum of its proper divisors (6424886527).

21961318145 is a wasteful number, since it uses less digits than its factorization.

21961318145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 64592.

The product of its digits is 51840, while the sum is 41.

The spelling of 21961318145 in words is "twenty-one billion, nine hundred sixty-one million, three hundred eighteen thousand, one hundred forty-five".