21157055 has 8 divisors (see below), whose sum is σ = 25462512. Its totient is φ = 16876288.

The previous prime is 21157049. The next prime is 21157067. The reversal of 21157055 is 55075112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21157055 - 2⁴ = 21157039 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 7 ways as a sum of consecutive naturals, for example, 4229 + ... + 7758.

It is an arithmetic number, because the mean of its divisors is an integer number (3182814).

Almost surely, 2^21157055 is an apocalyptic number.

21157055 is a deficient number, since it is larger than the sum of its proper divisors (4305457).

21157055 is a wasteful number, since it uses less digits than its factorization.

21157055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12345.

The product of its (nonzero) digits is 1750, while the sum is 26.

The square root of 21157055 is about 4599.6798801656. The cubic root of 21157055 is about 276.5784924094.

The spelling of 21157055 in words is "twenty-one million, one hundred fifty-seven thousand, fifty-five".