21213340155 has 32 divisors (see below), whose sum is σ = 43100121600. Its totient is φ = 9697526496.

The previous prime is 21213340121. The next prime is 21213340157. The reversal of 21213340155 is 55104331212.

It is not a de Polignac number, because 21213340155 - 2⁸ = 21213339899 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21213340157) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 11223045 + ... + 11224934.

It is an arithmetic number, because the mean of its divisors is an integer number (1346878800).

Almost surely, 2^21213340155 is an apocalyptic number.

21213340155 is an abundant number, since it is smaller than the sum of its proper divisors (21886781445).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21213340155 is a wasteful number, since it uses less digits than its factorization.

21213340155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22448000 (or 22447994 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

Adding to 21213340155 its reverse (55104331212), we get a palindrome (76317671367).

The spelling of 21213340155 in words is "twenty-one billion, two hundred thirteen million, three hundred forty thousand, one hundred fifty-five".