21177760661 has 8 divisors (see below), whose sum is σ = 21918021120. Its totient is φ = 20438166448.

The previous prime is 21177760657. The next prime is 21177760673. The reversal of 21177760661 is 16606777112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21177760661 - 2² = 21177760657 is a prime.

It is a super-2 number, since 2×21177760661² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21177760621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 101441 + ... + 229446.

It is an arithmetic number, because the mean of its divisors is an integer number (2739752640).

Almost surely, 2^21177760661 is an apocalyptic number.

It is an amenable number.

21177760661 is a deficient number, since it is larger than the sum of its proper divisors (740260459).

21177760661 is a wasteful number, since it uses less digits than its factorization.

21177760661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333123.

The product of its (nonzero) digits is 148176, while the sum is 44.

The spelling of 21177760661 in words is "twenty-one billion, one hundred seventy-seven million, seven hundred sixty thousand, six hundred sixty-one".