21623355387 has 12 divisors (see below), whose sum is σ = 31239582400. Its totient is φ = 14412871728.

The previous prime is 21623355373. The next prime is 21623355409. The reversal of 21623355387 is 78355332612.

21623355387 is a `hidden beast` number, since 2 + 1 + 62 + 33 + 553 + 8 + 7 = 666.

It is a de Polignac number, because none of the positive numbers 2^k-21623355387 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21623355287) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 173512 + ... + 270837.

Almost surely, 2^21623355387 is an apocalyptic number.

21623355387 is a deficient number, since it is larger than the sum of its proper divisors (9616227013).

21623355387 is a wasteful number, since it uses less digits than its factorization.

21623355387 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 449762 (or 449759 counting only the distinct ones).

The product of its digits is 907200, while the sum is 45.

Adding to 21623355387 its reverse (78355332612), we get a palindrome (99978687999).

The spelling of 21623355387 in words is "twenty-one billion, six hundred twenty-three million, three hundred fifty-five thousand, three hundred eighty-seven".