21154157 has 2 divisors, whose sum is σ = 21154158. Its totient is φ = 21154156.

The previous prime is 21154153. The next prime is 21154187. The reversal of 21154157 is 75145112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17355556 + 3798601 = 4166^2 + 1949^2 .

It is a cyclic number.

It is not a de Polignac number, because 21154157 - 2² = 21154153 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21154153) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10577078 + 10577079.

It is an arithmetic number, because the mean of its divisors is an integer number (10577079).

Almost surely, 2^21154157 is an apocalyptic number.

It is an amenable number.

21154157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21154157 is an equidigital number, since it uses as much as digits as its factorization.

21154157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1400, while the sum is 26.

The square root of 21154157 is about 4599.3648474545. The cubic root of 21154157 is about 276.5658636658.

Adding to 21154157 its reverse (75145112), we get a palindrome (96299269).

The spelling of 21154157 in words is "twenty-one million, one hundred fifty-four thousand, one hundred fifty-seven".