21157412 has 12 divisors (see below), whose sum is σ = 38974320. Its totient is φ = 10021896.

The previous prime is 21157403. The next prime is 21157429. The reversal of 21157412 is 21475112.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 139118 + ... + 139269.

It is an arithmetic number, because the mean of its divisors is an integer number (3247860).

Almost surely, 2^21157412 is an apocalyptic number.

It is an amenable number.

21157412 is a deficient number, since it is larger than the sum of its proper divisors (17816908).

21157412 is a wasteful number, since it uses less digits than its factorization.

21157412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 278410 (or 278408 counting only the distinct ones).

The product of its digits is 560, while the sum is 23.

The square root of 21157412 is about 4599.7186870503. The cubic root of 21157412 is about 276.5800480444.

The spelling of 21157412 in words is "twenty-one million, one hundred fifty-seven thousand, four hundred twelve".