21492157 has 2 divisors, whose sum is σ = 21492158. Its totient is φ = 21492156.

The previous prime is 21492151. The next prime is 21492167. The reversal of 21492157 is 75129412.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21427641 + 64516 = 4629^2 + 254^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21492157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21492151) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10746078 + 10746079.

It is an arithmetic number, because the mean of its divisors is an integer number (10746079).

Almost surely, 2^21492157 is an apocalyptic number.

It is an amenable number.

21492157 is a deficient number, since it is larger than the sum of its proper divisors (1).

21492157 is an equidigital number, since it uses as much as digits as its factorization.

21492157 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5040, while the sum is 31.

The square root of 21492157 is about 4635.9634381647. The cubic root of 21492157 is about 278.0310723856.

The spelling of 21492157 in words is "twenty-one million, four hundred ninety-two thousand, one hundred fifty-seven".