21358434387 has 6 divisors (see below), whose sum is σ = 28478250028. Its totient is φ = 14238787504.

The previous prime is 21358434379. The next prime is 21358434443. The reversal of 21358434387 is 78343485312.

It is not a de Polignac number, because 21358434387 - 2³ = 21358434379 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21358435387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 210943 + ... + 295319.

Almost surely, 2^21358434387 is an apocalyptic number.

21358434387 is a deficient number, since it is larger than the sum of its proper divisors (7119815641).

21358434387 is an frugal number, since it uses more digits than its factorization.

21358434387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168757 (or 84380 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 48.

Multiplying 21358434387 by its sum of digits (48), we get a square (1025204850576 = 1012524²).

The spelling of 21358434387 in words is "twenty-one billion, three hundred fifty-eight million, four hundred thirty-four thousand, three hundred eighty-seven".