21516351346531 has 4 divisors (see below), whose sum is σ = 21516496350232. Its totient is φ = 21516206342832.

The previous prime is 21516351346517. The next prime is 21516351346537. The reversal of 21516351346531 is 13564315361512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21516351346531 - 2⁹ = 21516351346019 is a prime.

It is a super-2 number, since 2×21516351346531² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21516351346537) 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, 72279045 + ... + 72576118.

It is an arithmetic number, because the mean of its divisors is an integer number (5379124087558).

Almost surely, 2^{21516351346531} is an apocalyptic number.

21516351346531 is a deficient number, since it is larger than the sum of its proper divisors (145003701).

21516351346531 is a wasteful number, since it uses less digits than its factorization.

21516351346531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 145003700.

The product of its digits is 972000, while the sum is 46.

The spelling of 21516351346531 in words is "twenty-one trillion, five hundred sixteen billion, three hundred fifty-one million, three hundred forty-six thousand, five hundred thirty-one".