21016570 has 8 divisors (see below), whose sum is σ = 37829844. Its totient is φ = 8406624.

The previous prime is 21016547. The next prime is 21016577. The reversal of 21016570 is 7561012.

It can be written as a sum of positive squares in 2 ways, for example, as 18757561 + 2259009 = 4331^2 + 1503^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a zygodrome in base 4.

It is not an unprimeable number, because it can be changed into a prime (21016577) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1050819 + ... + 1050838.

Almost surely, 2^21016570 is an apocalyptic number.

21016570 is a deficient number, since it is larger than the sum of its proper divisors (16813274).

21016570 is a wasteful number, since it uses less digits than its factorization.

21016570 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2101664.

The product of its (nonzero) digits is 420, while the sum is 22.

The square root of 21016570 is about 4584.3832736803. The cubic root of 21016570 is about 275.9649626461.

Adding to 21016570 its reverse (7561012), we get a palindrome (28577582).

The spelling of 21016570 in words is "twenty-one million, sixteen thousand, five hundred seventy".