7940740021 has 4 divisors (see below), whose sum is σ = 7942378444. Its totient is φ = 7939101600.

The previous prime is 7940740013. The next prime is 7940740051. The reversal of 7940740021 is 1200470497.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 6459336900 + 1481403121 = 80370^2 + 38489^2 .

It is a cyclic number.

It is not a de Polignac number, because 7940740021 - 2³ = 7940740013 is a prime.

It is a super-2 number, since 2×7940740021² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7940740051) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 811920 + ... + 821641.

It is an arithmetic number, because the mean of its divisors is an integer number (1985594611).

Almost surely, 2^7940740021 is an apocalyptic number.

It is an amenable number.

7940740021 is a deficient number, since it is larger than the sum of its proper divisors (1638423).

7940740021 is a wasteful number, since it uses less digits than its factorization.

7940740021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1638422.

The product of its (nonzero) digits is 14112, while the sum is 34.

The square root of 7940740021 is about 89110.8299871570. The cubic root of 7940740021 is about 1995.0494244282.

The spelling of 7940740021 in words is "seven billion, nine hundred forty million, seven hundred forty thousand, twenty-one".