21388681377 has 24 divisors (see below), whose sum is σ = 35419715136. Its totient is φ = 12183536736.

The previous prime is 21388681367. The next prime is 21388681397. The reversal of 21388681377 is 77318688312.

It is not a de Polignac number, because 21388681377 - 2⁶ = 21388681313 is a prime.

It is a super-2 number, since 2×21388681377² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21388681367) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 515523 + ... + 555464.

It is an arithmetic number, because the mean of its divisors is an integer number (1475821464).

Almost surely, 2^21388681377 is an apocalyptic number.

It is an amenable number.

21388681377 is a deficient number, since it is larger than the sum of its proper divisors (14031033759).

21388681377 is a wasteful number, since it uses less digits than its factorization.

21388681377 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1071317 (or 1071314 counting only the distinct ones).

The product of its digits is 2709504, while the sum is 54.

The spelling of 21388681377 in words is "twenty-one billion, three hundred eighty-eight million, six hundred eighty-one thousand, three hundred seventy-seven".