21154155 has 64 divisors (see below), whose sum is σ = 39191040. Its totient is φ = 9651200.

The previous prime is 21154153. The next prime is 21154157. The reversal of 21154155 is 55145112.

It is an interprime number because it is at equal distance from previous prime (21154153) and next prime (21154157).

It is not a de Polignac number, because 21154155 - 2¹ = 21154153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21154153) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 358516 + ... + 358574.

It is an arithmetic number, because the mean of its divisors is an integer number (612360).

Almost surely, 2^21154155 is an apocalyptic number.

21154155 is a deficient number, since it is larger than the sum of its proper divisors (18036885).

21154155 is a wasteful number, since it uses less digits than its factorization.

21154155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172.

The product of its digits is 1000, while the sum is 24.

The square root of 21154155 is about 4599.3646300332. The cubic root of 21154155 is about 276.5658549499.

Adding to 21154155 its reverse (55145112), we get a palindrome (76299267).

The spelling of 21154155 in words is "twenty-one million, one hundred fifty-four thousand, one hundred fifty-five".