21011221533 has 8 divisors (see below), whose sum is σ = 29233003968. Its totient is φ = 13398460064.

The previous prime is 21011221531. The next prime is 21011221577. The reversal of 21011221533 is 33512211012.

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 21011221533 - 2¹ = 21011221531 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21011221531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 152255160 + ... + 152255297.

It is an arithmetic number, because the mean of its divisors is an integer number (3654125496).

Almost surely, 2^21011221533 is an apocalyptic number.

21011221533 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21011221533 is a deficient number, since it is larger than the sum of its proper divisors (8221782435).

21011221533 is a wasteful number, since it uses less digits than its factorization.

21011221533 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 304510483.

The product of its (nonzero) digits is 360, while the sum is 21.

Adding to 21011221533 its reverse (33512211012), we get a palindrome (54523432545).

The spelling of 21011221533 in words is "twenty-one billion, eleven million, two hundred twenty-one thousand, five hundred thirty-three".