61890821 has 4 divisors (see below), whose sum is σ = 61942092. Its totient is φ = 61839552.

The previous prime is 61890799. The next prime is 61890839. The reversal of 61890821 is 12809816.

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 20802721 + 41088100 = 4561^2 + 6410^2 .

It is a cyclic number.

It is not a de Polignac number, because 61890821 - 2⁶ = 61890757 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61890841) 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, 23780 + ... + 26253.

It is an arithmetic number, because the mean of its divisors is an integer number (15485523).

Almost surely, 2^61890821 is an apocalyptic number.

It is an amenable number.

61890821 is a deficient number, since it is larger than the sum of its proper divisors (51271).

61890821 is a wasteful number, since it uses less digits than its factorization.

61890821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51270.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 61890821 is about 7867.0719457750. The cubic root of 61890821 is about 395.5567026115.

The spelling of 61890821 in words is "sixty-one million, eight hundred ninety thousand, eight hundred twenty-one".