21154242455 has 16 divisors (see below), whose sum is σ = 25939384704. Its totient is φ = 16554259200.

The previous prime is 21154242443. The next prime is 21154242463. The reversal of 21154242455 is 55424245112.

It is not a de Polignac number, because 21154242455 - 2¹² = 21154238359 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 423059 + ... + 470411.

It is an arithmetic number, because the mean of its divisors is an integer number (1621211544).

Almost surely, 2^21154242455 is an apocalyptic number.

21154242455 is a deficient number, since it is larger than the sum of its proper divisors (4785142249).

21154242455 is a wasteful number, since it uses less digits than its factorization.

21154242455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49306.

The product of its digits is 64000, while the sum is 35.

Adding to 21154242455 its reverse (55424245112), we get a palindrome (76578487567).

The spelling of 21154242455 in words is "twenty-one billion, one hundred fifty-four million, two hundred forty-two thousand, four hundred fifty-five".