402647921 has 8 divisors (see below), whose sum is σ = 444197544. Its totient is φ = 362609280.

The previous prime is 402647893. The next prime is 402647923. The reversal of 402647921 is 129746204.

It can be written as a sum of positive squares in 4 ways, for example, as 7075600 + 395572321 = 2660^2 + 19889^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-402647921 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (402647923) 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, 377186 + ... + 378251.

It is an arithmetic number, because the mean of its divisors is an integer number (55524693).

Almost surely, 2^402647921 is an apocalyptic number.

402647921 is a gapful number since it is divisible by the number (41) formed by its first and last digit.

It is an amenable number.

402647921 is a deficient number, since it is larger than the sum of its proper divisors (41549623).

402647921 is a wasteful number, since it uses less digits than its factorization.

402647921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 755491.

The product of its (nonzero) digits is 24192, while the sum is 35.

The square root of 402647921 is about 20066.0888316583. The cubic root of 402647921 is about 738.4285626849.

The spelling of 402647921 in words is "four hundred two million, six hundred forty-seven thousand, nine hundred twenty-one".