21081578023 has 8 divisors (see below), whose sum is σ = 23619655440. Its totient is φ = 18647095680.

The previous prime is 21081578009. The next prime is 21081578039. The reversal of 21081578023 is 32087518012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21081578023 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21081578053) 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, 25898338 + ... + 25899151.

It is an arithmetic number, because the mean of its divisors is an integer number (2952456930).

Almost surely, 2^21081578023 is an apocalyptic number.

21081578023 is a deficient number, since it is larger than the sum of its proper divisors (2538077417).

21081578023 is a wasteful number, since it uses less digits than its factorization.

21081578023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51797537.

The product of its (nonzero) digits is 26880, while the sum is 37.

The spelling of 21081578023 in words is "twenty-one billion, eighty-one million, five hundred seventy-eight thousand, twenty-three".