21053133391 has 4 divisors (see below), whose sum is σ = 21120396112. Its totient is φ = 20985870672.

The previous prime is 21053133383. The next prime is 21053133397. The reversal of 21053133391 is 19333135012.

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 21053133391 - 2³ = 21053133383 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 (21053133397) 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, 33630891 + ... + 33631516.

It is an arithmetic number, because the mean of its divisors is an integer number (5280099028).

Almost surely, 2^21053133391 is an apocalyptic number.

21053133391 is a deficient number, since it is larger than the sum of its proper divisors (67262721).

21053133391 is an equidigital number, since it uses as much as digits as its factorization.

21053133391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67262720.

The product of its (nonzero) digits is 7290, while the sum is 31.

The spelling of 21053133391 in words is "twenty-one billion, fifty-three million, one hundred thirty-three thousand, three hundred ninety-one".