21405971958 has 32 divisors (see below), whose sum is σ = 48946470144. Its totient is φ = 6113675232.

The previous prime is 21405971947. The next prime is 21405971969. The reversal of 21405971958 is 85917950412.

It is an interprime number because it is at equal distance from previous prime (21405971947) and next prime (21405971969).

It is a self number, because there is not a number n which added to its sum of digits gives 21405971958.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 17241 + ... + 207627.

It is an arithmetic number, because the mean of its divisors is an integer number (1529577192).

Almost surely, 2^21405971958 is an apocalyptic number.

21405971958 is an abundant number, since it is smaller than the sum of its proper divisors (27540498186).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21405971958 is a wasteful number, since it uses less digits than its factorization.

21405971958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193076.

The product of its (nonzero) digits is 907200, while the sum is 51.

The spelling of 21405971958 in words is "twenty-one billion, four hundred five million, nine hundred seventy-one thousand, nine hundred fifty-eight".