21091520436 has 48 divisors (see below), whose sum is σ = 56285685120. Its totient is φ = 6021688320.

The previous prime is 21091520431. The next prime is 21091520473. The reversal of 21091520436 is 63402519012.

It is a junction number, because it is equal to n+sod(n) for n = 21091520397 and 21091520406.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21091520431) 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, 22080 + ... + 206568.

It is an arithmetic number, because the mean of its divisors is an integer number (1172618440).

Almost surely, 2^21091520436 is an apocalyptic number.

It is an amenable number.

21091520436 is an abundant number, since it is smaller than the sum of its proper divisors (35194164684).

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

21091520436 is a wasteful number, since it uses less digits than its factorization.

21091520436 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185864 (or 185862 counting only the distinct ones).

The product of its (nonzero) digits is 12960, while the sum is 33.

The spelling of 21091520436 in words is "twenty-one billion, ninety-one million, five hundred twenty thousand, four hundred thirty-six".