61421012721 has 64 divisors (see below), whose sum is σ = 96369530880. Its totient is φ = 38600064000.

The previous prime is 61421012713. The next prime is 61421012729. The reversal of 61421012721 is 12721012416.

61421012721 is a `hidden beast` number, since 614 + 2 + 1 + 0 + 1 + 27 + 21 = 666.

It is an interprime number because it is at equal distance from previous prime (61421012713) and next prime (61421012729).

It is not a de Polignac number, because 61421012721 - 2³ = 61421012713 is a prime.

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (61421012729) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 35036781 + ... + 35038533.

It is an arithmetic number, because the mean of its divisors is an integer number (1505773920).

Almost surely, 2^61421012721 is an apocalyptic number.

It is an amenable number.

61421012721 is a deficient number, since it is larger than the sum of its proper divisors (34948518159).

61421012721 is a wasteful number, since it uses less digits than its factorization.

61421012721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2855 (or 2849 counting only the distinct ones).

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

The spelling of 61421012721 in words is "sixty-one billion, four hundred twenty-one million, twelve thousand, seven hundred twenty-one".