21011511234 has 32 divisors (see below), whose sum is σ = 49324323456. Its totient is φ = 5841037440.

The previous prime is 21011511229. The next prime is 21011511239. The reversal of 21011511234 is 43211511012.

It is an interprime number because it is at equal distance from previous prime (21011511229) and next prime (21011511239).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 21011511234.

It is not an unprimeable number, because it can be changed into a prime (21011511239) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6758907 + ... + 6762014.

It is an arithmetic number, because the mean of its divisors is an integer number (1541385108).

Almost surely, 2^21011511234 is an apocalyptic number.

21011511234 is an abundant number, since it is smaller than the sum of its proper divisors (28312812222).

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

21011511234 is a wasteful number, since it uses less digits than its factorization.

21011511234 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13520970.

The product of its (nonzero) digits is 240, while the sum is 21.

The spelling of 21011511234 in words is "twenty-one billion, eleven million, five hundred eleven thousand, two hundred thirty-four".