61810021 has 24 divisors (see below), whose sum is σ = 81523680. Its totient is φ = 46321632.

The previous prime is 61810009. The next prime is 61810033. The reversal of 61810021 is 12001816.

It is an interprime number because it is at equal distance from previous prime (61810009) and next prime (61810033).

It is not a de Polignac number, because 61810021 - 2⁷ = 61809893 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61810051) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9550 + ... + 14656.

It is an arithmetic number, because the mean of its divisors is an integer number (3396820).

Almost surely, 2^61810021 is an apocalyptic number.

It is an amenable number.

61810021 is a deficient number, since it is larger than the sum of its proper divisors (19713659).

61810021 is a wasteful number, since it uses less digits than its factorization.

61810021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5153 (or 5146 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 19.

The square root of 61810021 is about 7861.9349399496. The cubic root of 61810021 is about 395.3844912896.

Adding to 61810021 its reverse (12001816), we get a palindrome (73811837).

The spelling of 61810021 in words is "sixty-one million, eight hundred ten thousand, twenty-one".