39991021 has 8 divisors (see below), whose sum is σ = 48392640. Its totient is φ = 32261568.

The previous prime is 39991019. The next prime is 39991033. The reversal of 39991021 is 12019993.

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 39991021 - 2¹ = 39991019 is a prime.

It is a super-3 number, since 3×39991021³ (a number of 24 digits) contains 333 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 (39991121) 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, 167911 + ... + 168148.

It is an arithmetic number, because the mean of its divisors is an integer number (6049080).

Almost surely, 2^39991021 is an apocalyptic number.

It is an amenable number.

39991021 is a deficient number, since it is larger than the sum of its proper divisors (8401619).

39991021 is a wasteful number, since it uses less digits than its factorization.

39991021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336083.

The product of its (nonzero) digits is 4374, while the sum is 34.

The square root of 39991021 is about 6323.8454282185. The cubic root of 39991021 is about 341.9695976303.

The spelling of 39991021 in words is "thirty-nine million, nine hundred ninety-one thousand, twenty-one".