21221783311511 has 4 divisors (see below), whose sum is σ = 21221827090224. Its totient is φ = 21221739532800.

The previous prime is 21221783311409. The next prime is 21221783311513. The reversal of 21221783311511 is 11511338712212.

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 21221783311511 - 2²⁶ = 21221716202647 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21221783311513) 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, 21153995 + ... + 22134476.

It is an arithmetic number, because the mean of its divisors is an integer number (5305456772556).

Almost surely, 2^{21221783311511} is an apocalyptic number.

21221783311511 is a deficient number, since it is larger than the sum of its proper divisors (43778713).

21221783311511 is an equidigital number, since it uses as much as digits as its factorization.

21221783311511 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43778712.

The product of its digits is 20160, while the sum is 38.

The spelling of 21221783311511 in words is "twenty-one trillion, two hundred twenty-one billion, seven hundred eighty-three million, three hundred eleven thousand, five hundred eleven".