20626991 has 30 divisors (see below), whose sum is σ = 26822376. Its totient is φ = 15846600.

The previous prime is 20626981. The next prime is 20626993. The reversal of 20626991 is 19962602.

It is not a de Polignac number, because 20626991 - 2¹⁰ = 20625967 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20626993) by changing a digit.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 290486 + ... + 290556.

Almost surely, 2^20626991 is an apocalyptic number.

20626991 is a deficient number, since it is larger than the sum of its proper divisors (6195385).

20626991 is an frugal number, since it uses more digits than its factorization.

20626991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121 (or 89 counting only the distinct ones).

The product of its (nonzero) digits is 11664, while the sum is 35.

The square root of 20626991 is about 4541.6947277421. The cubic root of 20626991 is about 274.2491517820.

The spelling of 20626991 in words is "twenty million, six hundred twenty-six thousand, nine hundred ninety-one".