21661246155511 has 4 divisors (see below), whose sum is σ = 21661336069024. Its totient is φ = 21661156242000.

The previous prime is 21661246155467. The next prime is 21661246155517. The reversal of 21661246155511 is 11555164216612.

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 21661246155511 - 2⁴³ = 12865153133303 is a prime.

It is a super-2 number, since 2×21661246155511² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21661246155517) 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, 44594415 + ... + 45077536.

It is an arithmetic number, because the mean of its divisors is an integer number (5415334017256).

Almost surely, 2^{21661246155511} is an apocalyptic number.

21661246155511 is a deficient number, since it is larger than the sum of its proper divisors (89913513).

21661246155511 is an equidigital number, since it uses as much as digits as its factorization.

21661246155511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 89913512.

The product of its digits is 432000, while the sum is 46.

The spelling of 21661246155511 in words is "twenty-one trillion, six hundred sixty-one billion, two hundred forty-six million, one hundred fifty-five thousand, five hundred eleven".