21131277641 has 6 divisors (see below), whose sum is σ = 21319947870. Its totient is φ = 20944262528.

The previous prime is 21131277617. The next prime is 21131277649. The reversal of 21131277641 is 14677213112.

It can be written as a sum of positive squares in 3 ways, for example, as 3387705616 + 17743572025 = 58204^2 + 133205^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21131277641 is a prime.

It is a Duffinian number.

21131277641 is a modest number, since divided by 277641 gives 21131 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21131277649) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 814676 + ... + 840213.

It is an arithmetic number, because the mean of its divisors is an integer number (3553324645).

Almost surely, 2^21131277641 is an apocalyptic number.

It is an amenable number.

21131277641 is a deficient number, since it is larger than the sum of its proper divisors (188670229).

21131277641 is an equidigital number, since it uses as much as digits as its factorization.

21131277641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1655115 (or 1655002 counting only the distinct ones).

The product of its digits is 14112, while the sum is 35.

The spelling of 21131277641 in words is "twenty-one billion, one hundred thirty-one million, two hundred seventy-seven thousand, six hundred forty-one".