651261721 has 32 divisors (see below), whose sum is σ = 800057088. Its totient is φ = 522762240.

The previous prime is 651261719. The next prime is 651261739. The reversal of 651261721 is 127162156.

It is not a de Polignac number, because 651261721 - 2¹ = 651261719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (651261761) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 226525 + ... + 229381.

It is an arithmetic number, because the mean of its divisors is an integer number (25001784).

Almost surely, 2^651261721 is an apocalyptic number.

It is an amenable number.

651261721 is a deficient number, since it is larger than the sum of its proper divisors (148795367).

651261721 is a wasteful number, since it uses less digits than its factorization.

651261721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2961.

The product of its digits is 5040, while the sum is 31.

The square root of 651261721 is about 25519.8299563300. The cubic root of 651261721 is about 866.7992313163.

The spelling of 651261721 in words is "six hundred fifty-one million, two hundred sixty-one thousand, seven hundred twenty-one".