21561067 has 16 divisors (see below), whose sum is σ = 25125120. Its totient is φ = 18295200.

The previous prime is 21561041. The next prime is 21561077. The reversal of 21561067 is 76016512.

It is not a de Polignac number, because 21561067 - 2⁷ = 21560939 is a prime.

It is a super-2 number, since 2×21561067² = 929759220356978, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21561077) 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, 14113 + ... + 15565.

It is an arithmetic number, because the mean of its divisors is an integer number (1570320).

Almost surely, 2^21561067 is an apocalyptic number.

21561067 is a deficient number, since it is larger than the sum of its proper divisors (3564053).

21561067 is a wasteful number, since it uses less digits than its factorization.

21561067 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1554.

The product of its (nonzero) digits is 2520, while the sum is 28.

The square root of 21561067 is about 4643.3896024348. The cubic root of 21561067 is about 278.3279044044.

Adding to 21561067 its reverse (76016512), we get a palindrome (97577579).

Subtracting 21561067 from its reverse (76016512), we obtain a palindrome (54455445).

It can be divided in two parts, 2156 and 1067, that added together give a palindrome (3223).

The spelling of 21561067 in words is "twenty-one million, five hundred sixty-one thousand, sixty-seven".