21756616377 has 4 divisors (see below), whose sum is σ = 29008821840. Its totient is φ = 14504410916.

The previous prime is 21756616373. The next prime is 21756616381. The reversal of 21756616377 is 77361665712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is an interprime number because it is at equal distance from previous prime (21756616373) and next prime (21756616381).

It is a cyclic number.

It is not a de Polignac number, because 21756616377 - 2² = 21756616373 is a prime.

It is a super-3 number, since 3×21756616377³ (a number of 32 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (21756616373) 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, 3626102727 + ... + 3626102732.

It is an arithmetic number, because the mean of its divisors is an integer number (7252205460).

Almost surely, 2^21756616377 is an apocalyptic number.

It is an amenable number.

21756616377 is a deficient number, since it is larger than the sum of its proper divisors (7252205463).

21756616377 is an equidigital number, since it uses as much as digits as its factorization.

21756616377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7252205462.

The product of its digits is 2222640, while the sum is 51.

The spelling of 21756616377 in words is "twenty-one billion, seven hundred fifty-six million, six hundred sixteen thousand, three hundred seventy-seven".