21071956 has 24 divisors (see below), whose sum is σ = 38687040. Its totient is φ = 10023552.

The previous prime is 21071927. The next prime is 21071977. The reversal of 21071956 is 65917012.

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, 20380 + ... + 21388.

It is an arithmetic number, because the mean of its divisors is an integer number (1611960).

Almost surely, 2^21071956 is an apocalyptic number.

It is an amenable number.

21071956 is a deficient number, since it is larger than the sum of its proper divisors (17615084).

21071956 is a wasteful number, since it uses less digits than its factorization.

21071956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1263 (or 1261 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 31.

The square root of 21071956 is about 4590.4200243551. The cubic root of 21071956 is about 276.2071713461.

Adding to 21071956 its reverse (65917012), we get a palindrome (86988968).

The spelling of 21071956 in words is "twenty-one million, seventy-one thousand, nine hundred fifty-six".