21305720078 has 8 divisors (see below), whose sum is σ = 31966834872. Its totient is φ = 10650108456.

The previous prime is 21305720077. The next prime is 21305720113. The reversal of 21305720078 is 87002750312.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305720077) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1366100 + ... + 1381607.

It is an arithmetic number, because the mean of its divisors is an integer number (3995854359).

Almost surely, 2^21305720078 is an apocalyptic number.

21305720078 is a deficient number, since it is larger than the sum of its proper divisors (10661114794).

21305720078 is a wasteful number, since it uses less digits than its factorization.

21305720078 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2751586.

The product of its (nonzero) digits is 23520, while the sum is 35.

The spelling of 21305720078 in words is "twenty-one billion, three hundred five million, seven hundred twenty thousand, seventy-eight".