61028721 has 24 divisors (see below), whose sum is σ = 98454720. Its totient is φ = 37554192.

The previous prime is 61028719. The next prime is 61028743. The reversal of 61028721 is 12782016.

61028721 is a `hidden beast` number, since 610 + 28 + 7 + 21 = 666.

It is not a de Polignac number, because 61028721 - 2¹ = 61028719 is a prime.

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

It is not an unprimeable number, because it can be changed into a prime (61028711) 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, 6501 + ... + 12818.

It is an arithmetic number, because the mean of its divisors is an integer number (4102280).

Almost surely, 2^61028721 is an apocalyptic number.

It is an amenable number.

61028721 is a deficient number, since it is larger than the sum of its proper divisors (37425999).

61028721 is a wasteful number, since it uses less digits than its factorization.

61028721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19347 (or 19335 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 61028721 is about 7812.0881331434. The cubic root of 61028721 is about 393.7114901113.

The spelling of 61028721 in words is "sixty-one million, twenty-eight thousand, seven hundred twenty-one".