6921720 has 256 divisors, whose sum is σ = 27216000. Its totient is φ = 1548288.

The previous prime is 6921709. The next prime is 6921727. The reversal of 6921720 is 271296.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6921727) 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, 238666 + ... + 238694.

Almost surely, 2^6921720 is an apocalyptic number.

6921720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 6921720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13608000).

6921720 is an abundant number, since it is smaller than the sum of its proper divisors (20294280).

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

6921720 is a wasteful number, since it uses less digits than its factorization.

6921720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 79 (or 69 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 6921720 is about 2630.9161902273. The cubic root of 6921720 is about 190.5773757227.

The spelling of 6921720 in words is "six million, nine hundred twenty-one thousand, seven hundred twenty".