61910021 has 4 divisors (see below), whose sum is σ = 62121612. Its totient is φ = 61698432.

The previous prime is 61910011. The next prime is 61910027. The reversal of 61910021 is 12001916.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 53436100 + 8473921 = 7310^2 + 2911^2 .

It is a cyclic number.

It is not a de Polignac number, because 61910021 - 2⁶ = 61909957 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 61909975 and 61910002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61910027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105356 + ... + 105941.

It is an arithmetic number, because the mean of its divisors is an integer number (15530403).

Almost surely, 2^61910021 is an apocalyptic number.

It is an amenable number.

61910021 is a deficient number, since it is larger than the sum of its proper divisors (211591).

61910021 is a wasteful number, since it uses less digits than its factorization.

61910021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211590.

The product of its (nonzero) digits is 108, while the sum is 20.

The square root of 61910021 is about 7868.2921272662. The cubic root of 61910021 is about 395.5976020715.

Adding to 61910021 its reverse (12001916), we get a palindrome (73911937).

The spelling of 61910021 in words is "sixty-one million, nine hundred ten thousand, twenty-one".