21601000 has 32 divisors (see below), whose sum is σ = 50548680. Its totient is φ = 8640000.

The previous prime is 21600991. The next prime is 21601061. The reversal of 21601000 is 10612.

It can be written as a sum of positive squares in 4 ways, for example, as 11142244 + 10458756 = 3338^2 + 3234^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

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, 9801 + ... + 11800.

Almost surely, 2^21601000 is an apocalyptic number.

21601000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21601000 is an abundant number, since it is smaller than the sum of its proper divisors (28947680).

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

21601000 is a wasteful number, since it uses less digits than its factorization.

21601000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21622 (or 21608 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21601000 is about 4647.6875970745. The cubic root of 21601000 is about 278.4996277179.

Adding to 21601000 its reverse (10612), we get a palindrome (21611612).

It can be divided in two parts, 2160 and 1000, that added together give a triangular number (3160 = T₇₉).

The spelling of 21601000 in words is "twenty-one million, six hundred one thousand".