61639220 has 24 divisors (see below), whose sum is σ = 129592008. Its totient is φ = 24627200.

The previous prime is 61639213. The next prime is 61639271. The reversal of 61639220 is 2293616.

It can be written as a sum of positive squares in 4 ways, for example, as 3055504 + 58583716 = 1748^2 + 7654^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 28580 + ... + 30660.

It is an arithmetic number, because the mean of its divisors is an integer number (5399667).

Almost surely, 2^61639220 is an apocalyptic number.

It is an amenable number.

61639220 is an abundant number, since it is smaller than the sum of its proper divisors (67952788).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

61639220 is a wasteful number, since it uses less digits than its factorization.

61639220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3571 (or 3569 counting only the distinct ones).

The product of its (nonzero) digits is 3888, while the sum is 29.

The square root of 61639220 is about 7851.0648959234. The cubic root of 61639220 is about 395.0199637402.

The spelling of 61639220 in words is "sixty-one million, six hundred thirty-nine thousand, two hundred twenty".