21115351531 has 8 divisors (see below), whose sum is σ = 21251022624. Its totient is φ = 20980115520.

The previous prime is 21115351513. The next prime is 21115351571. The reversal of 21115351531 is 13515351112.

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 21115351531 - 2¹³ = 21115343339 is a prime.

It is a super-2 number, since 2×21115351531² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21115351531.

It is not an unprimeable number, because it can be changed into a prime (21115351571) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11116 + ... + 205801.

It is an arithmetic number, because the mean of its divisors is an integer number (2656377828).

Almost surely, 2^21115351531 is an apocalyptic number.

21115351531 is a deficient number, since it is larger than the sum of its proper divisors (135671093).

21115351531 is a wasteful number, since it uses less digits than its factorization.

21115351531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 217541.

The product of its digits is 2250, while the sum is 28.

The spelling of 21115351531 in words is "twenty-one billion, one hundred fifteen million, three hundred fifty-one thousand, five hundred thirty-one".