21065723438 has 8 divisors (see below), whose sum is σ = 31604467032. Its totient is φ = 10530901096.

The previous prime is 21065723429. The next prime is 21065723447. The reversal of 21065723438 is 83432756012.

It is an interprime number because it is at equal distance from previous prime (21065723429) and next prime (21065723447).

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

It is a junction number, because it is equal to n+sod(n) for n = 21065723395 and 21065723404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 966845 + ... + 988392.

It is an arithmetic number, because the mean of its divisors is an integer number (3950558379).

Almost surely, 2^21065723438 is an apocalyptic number.

21065723438 is a deficient number, since it is larger than the sum of its proper divisors (10538743594).

21065723438 is a wasteful number, since it uses less digits than its factorization.

21065723438 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1960626.

The product of its (nonzero) digits is 241920, while the sum is 41.

The spelling of 21065723438 in words is "twenty-one billion, sixty-five million, seven hundred twenty-three thousand, four hundred thirty-eight".