21157694 has 4 divisors (see below), whose sum is σ = 31736544. Its totient is φ = 10578846.

The previous prime is 21157693. The next prime is 21157699. The reversal of 21157694 is 49675112.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21157693) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5289422 + ... + 5289425.

It is an arithmetic number, because the mean of its divisors is an integer number (7934136).

Almost surely, 2^21157694 is an apocalyptic number.

21157694 is a deficient number, since it is larger than the sum of its proper divisors (10578850).

21157694 is a wasteful number, since it uses less digits than its factorization.

21157694 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10578849.

The product of its digits is 15120, while the sum is 35.

The square root of 21157694 is about 4599.7493409967. The cubic root of 21157694 is about 276.5812768530.

The spelling of 21157694 in words is "twenty-one million, one hundred fifty-seven thousand, six hundred ninety-four".