21157826 has 16 divisors (see below), whose sum is σ = 33729696. Its totient is φ = 9919296.

The previous prime is 21157817. The next prime is 21157831. The reversal of 21157826 is 62875112.

It is a junction number, because it is equal to n+sod(n) for n = 21157792 and 21157801.

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, 9425 + ... + 11451.

It is an arithmetic number, because the mean of its divisors is an integer number (2108106).

Almost surely, 2^21157826 is an apocalyptic number.

21157826 is a deficient number, since it is larger than the sum of its proper divisors (12571870).

21157826 is a wasteful number, since it uses less digits than its factorization.

21157826 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2353.

The product of its digits is 6720, while the sum is 32.

The square root of 21157826 is about 4599.7636895823. The cubic root of 21157826 is about 276.5818520362.

The spelling of 21157826 in words is "twenty-one million, one hundred fifty-seven thousand, eight hundred twenty-six".