21061061 has 4 divisors (see below), whose sum is σ = 24069792. Its totient is φ = 18052332.

The previous prime is 21061057. The next prime is 21061069. The reversal of 21061061 is 16016012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21061061 - 2² = 21061057 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21061069) 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, 1504355 + ... + 1504368.

It is an arithmetic number, because the mean of its divisors is an integer number (6017448).

Almost surely, 2^21061061 is an apocalyptic number.

It is an amenable number.

21061061 is a deficient number, since it is larger than the sum of its proper divisors (3008731).

21061061 is an equidigital number, since it uses as much as digits as its factorization.

21061061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3008730.

The product of its (nonzero) digits is 72, while the sum is 17.

The square root of 21061061 is about 4589.2331603439. The cubic root of 21061061 is about 276.1595599470.

Adding to 21061061 its reverse (16016012), we get a palindrome (37077073).

The spelling of 21061061 in words is "twenty-one million, sixty-one thousand, sixty-one".