21154301557 has 4 divisors (see below), whose sum is σ = 21154598080. Its totient is φ = 21154005036.

The previous prime is 21154301537. The next prime is 21154301587. The reversal of 21154301557 is 75510345112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21154301557 - 2¹⁵ = 21154268789 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 (21154301507) 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, 30994 + ... + 208012.

It is an arithmetic number, because the mean of its divisors is an integer number (5288649520).

Almost surely, 2^21154301557 is an apocalyptic number.

It is an amenable number.

21154301557 is a deficient number, since it is larger than the sum of its proper divisors (296523).

21154301557 is a wasteful number, since it uses less digits than its factorization.

21154301557 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296522.

The product of its (nonzero) digits is 21000, while the sum is 34.

Adding to 21154301557 its reverse (75510345112), we get a palindrome (96664646669).

The spelling of 21154301557 in words is "twenty-one billion, one hundred fifty-four million, three hundred one thousand, five hundred fifty-seven".