21517153376421 has 8 divisors (see below), whose sum is σ = 28943427551040. Its totient is φ = 14217824059712.

The previous prime is 21517153376419. The next prime is 21517153376423. The reversal of 21517153376421 is 12467335171512.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21517153376419) and next prime (21517153376423).

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 21517153376421 - 2¹ = 21517153376419 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21517153376423) 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, 31736214081 + ... + 31736214758.

It is an arithmetic number, because the mean of its divisors is an integer number (3617928443880).

Almost surely, 2^{21517153376421} is an apocalyptic number.

It is an amenable number.

21517153376421 is a deficient number, since it is larger than the sum of its proper divisors (7426274174619).

21517153376421 is a wasteful number, since it uses less digits than its factorization.

21517153376421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63472428955.

The product of its digits is 1058400, while the sum is 48.

The spelling of 21517153376421 in words is "twenty-one trillion, five hundred seventeen billion, one hundred fifty-three million, three hundred seventy-six thousand, four hundred twenty-one".