21000738 has 32 divisors (see below), whose sum is σ = 48234240. Its totient is φ = 6028560.

The previous prime is 21000737. The next prime is 21000739. The reversal of 21000738 is 83700012.

It is an interprime number because it is at equal distance from previous prime (21000737) and next prime (21000739).

21000738 is a modest number, since divided by 738 gives 210 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21000731) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7120 + ... + 9627.

It is an arithmetic number, because the mean of its divisors is an integer number (1507320).

Almost surely, 2^21000738 is an apocalyptic number.

21000738 is an abundant number, since it is smaller than the sum of its proper divisors (27233502).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21000738 is a wasteful number, since it uses less digits than its factorization.

21000738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16782.

The product of its (nonzero) digits is 336, while the sum is 21.

The square root of 21000738 is about 4582.6562166499. The cubic root of 21000738 is about 275.8956494829.

The spelling of 21000738 in words is "twenty-one million, seven hundred thirty-eight", and thus it is an aban number.