21158356 has 6 divisors (see below), whose sum is σ = 37027130. Its totient is φ = 10579176.

The previous prime is 21158329. The next prime is 21158377. The reversal of 21158356 is 65385112.

It can be written as a sum of positive squares in only one way, i.e., 13205956 + 7952400 = 3634^2 + 2820^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2644791 + ... + 2644798.

Almost surely, 2^21158356 is an apocalyptic number.

It is an amenable number.

21158356 is a deficient number, since it is larger than the sum of its proper divisors (15868774).

21158356 is a wasteful number, since it uses less digits than its factorization.

21158356 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5289593 (or 5289591 counting only the distinct ones).

The product of its digits is 7200, while the sum is 31.

The square root of 21158356 is about 4599.8213008768. The cubic root of 21158356 is about 276.5841614600.

The spelling of 21158356 in words is "twenty-one million, one hundred fifty-eight thousand, three hundred fifty-six".