21515979743 has 8 divisors (see below), whose sum is σ = 21548243376. Its totient is φ = 21483740800.

The previous prime is 21515979733. The next prime is 21515979769. The reversal of 21515979743 is 34797951512.

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

It is a cyclic number.

It is not a de Polignac number, because 21515979743 - 2⁶ = 21515979679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21515979733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2375303 + ... + 2384343.

It is an arithmetic number, because the mean of its divisors is an integer number (2693530422).

Almost surely, 2^21515979743 is an apocalyptic number.

21515979743 is a deficient number, since it is larger than the sum of its proper divisors (32263633).

21515979743 is a wasteful number, since it uses less digits than its factorization.

21515979743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12345.

The product of its digits is 2381400, while the sum is 53.

The spelling of 21515979743 in words is "twenty-one billion, five hundred fifteen million, nine hundred seventy-nine thousand, seven hundred forty-three".