721401840 has 60 divisors (see below), whose sum is σ = 2422710264. Its totient is φ = 192373632.

The previous prime is 721401787. The next prime is 721401853. The reversal of 721401840 is 48104127.

It is a tau number, because it is divible by the number of its divisors (60).

It is a super-2 number, since 2×721401840² = 1040841229510771200, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 500254 + ... + 501693.

Almost surely, 2^721401840 is an apocalyptic number.

It is an amenable number.

721401840 is an abundant number, since it is smaller than the sum of its proper divisors (1701308424).

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

721401840 is a wasteful number, since it uses less digits than its factorization.

721401840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1001966 (or 1001957 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 27.

The square root of 721401840 is about 26858.9247737135. The cubic root of 721401840 is about 896.8622585409.

Adding to 721401840 its reverse (48104127), we get a palindrome (769505967).

The spelling of 721401840 in words is "seven hundred twenty-one million, four hundred one thousand, eight hundred forty".