21157115 has 16 divisors (see below), whose sum is σ = 29369088. Its totient is φ = 14330976.

The previous prime is 21157111. The next prime is 21157117. The reversal of 21157115 is 51175112.

It is a cyclic number.

It is not a de Polignac number, because 21157115 - 2² = 21157111 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21157111) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 737 + ... + 6546.

It is an arithmetic number, because the mean of its divisors is an integer number (1835568).

Almost surely, 2^21157115 is an apocalyptic number.

21157115 is a deficient number, since it is larger than the sum of its proper divisors (8211973).

21157115 is an equidigital number, since it uses as much as digits as its factorization.

21157115 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7378.

The product of its digits is 350, while the sum is 23.

The square root of 21157115 is about 4599.6864023540. The cubic root of 21157115 is about 276.5787538619.

The spelling of 21157115 in words is "twenty-one million, one hundred fifty-seven thousand, one hundred fifteen".