40721921 has 4 divisors (see below), whose sum is σ = 42865200. Its totient is φ = 38578644.

The previous prime is 40721917. The next prime is 40721927. The reversal of 40721921 is 12912704.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 40721921 - 2² = 40721917 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (40721927) 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, 1071611 + ... + 1071648.

It is an arithmetic number, because the mean of its divisors is an integer number (10716300).

Almost surely, 2^40721921 is an apocalyptic number.

It is an amenable number.

40721921 is a deficient number, since it is larger than the sum of its proper divisors (2143279).

40721921 is a wasteful number, since it uses less digits than its factorization.

40721921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2143278.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 40721921 is about 6381.3729713910. The cubic root of 40721921 is about 344.0403802652.

The spelling of 40721921 in words is "forty million, seven hundred twenty-one thousand, nine hundred twenty-one".