21099599531 has 2 divisors, whose sum is σ = 21099599532. Its totient is φ = 21099599530.

The previous prime is 21099599509. The next prime is 21099599593. The reversal of 21099599531 is 13599599012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21099599531 - 2³⁰ = 20025857707 is a prime.

It is a super-2 number, since 2×21099599531² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21099599431) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10549799765 + 10549799766.

It is an arithmetic number, because the mean of its divisors is an integer number (10549799766).

Almost surely, 2^21099599531 is an apocalyptic number.

21099599531 is a deficient number, since it is larger than the sum of its proper divisors (1).

21099599531 is an equidigital number, since it uses as much as digits as its factorization.

21099599531 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 984150, while the sum is 53.

The spelling of 21099599531 in words is "twenty-one billion, ninety-nine million, five hundred ninety-nine thousand, five hundred thirty-one".