61306821 has 16 divisors (see below), whose sum is σ = 91523520. Its totient is φ = 40556880.

The previous prime is 61306801. The next prime is 61306831. The reversal of 61306821 is 12860316.

It is not a de Polignac number, because 61306821 - 2⁶ = 61306757 is a prime.

It is a super-2 number, since 2×61306821² = 7517052602252082, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61306801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5130 + ... + 12203.

It is an arithmetic number, because the mean of its divisors is an integer number (5720220).

Almost surely, 2^61306821 is an apocalyptic number.

It is an amenable number.

61306821 is a deficient number, since it is larger than the sum of its proper divisors (30216699).

61306821 is a wasteful number, since it uses less digits than its factorization.

61306821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17473 (or 17467 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 61306821 is about 7829.8672402538. The cubic root of 61306821 is about 394.3086148257.

It can be divided in two parts, 613068 and 21, that added together give a square (613089 = 783²).

The spelling of 61306821 in words is "sixty-one million, three hundred six thousand, eight hundred twenty-one".