651997921 has 8 divisors (see below), whose sum is σ = 677321984. Its totient is φ = 626942160.

The previous prime is 651997877. The next prime is 651997937. The reversal of 651997921 is 129799156.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 651997921 - 2⁷ = 651997793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (651992921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62115 + ... + 71848.

It is an arithmetic number, because the mean of its divisors is an integer number (84665248).

Almost surely, 2^651997921 is an apocalyptic number.

It is an amenable number.

651997921 is a deficient number, since it is larger than the sum of its proper divisors (25324063).

651997921 is a wasteful number, since it uses less digits than its factorization.

651997921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 134151.

The product of its digits is 306180, while the sum is 49.

The square root of 651997921 is about 25534.2499596131. The cubic root of 651997921 is about 867.1257243732.

The spelling of 651997921 in words is "six hundred fifty-one million, nine hundred ninety-seven thousand, nine hundred twenty-one".