21506473357 has 8 divisors (see below), whose sum is σ = 22809432960. Its totient is φ = 20234171760.

The previous prime is 21506473343. The next prime is 21506473379. The reversal of 21506473357 is 75337460512.

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 21506473357 - 2¹⁵ = 21506440589 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 (21506473327) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7663057 + ... + 7665862.

It is an arithmetic number, because the mean of its divisors is an integer number (2851179120).

Almost surely, 2^21506473357 is an apocalyptic number.

It is an amenable number.

21506473357 is a deficient number, since it is larger than the sum of its proper divisors (1302959603).

21506473357 is a wasteful number, since it uses less digits than its factorization.

21506473357 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15329003.

The product of its (nonzero) digits is 529200, while the sum is 43.

The spelling of 21506473357 in words is "twenty-one billion, five hundred six million, four hundred seventy-three thousand, three hundred fifty-seven".